Rework app into a class

This simplifies usage, goes from

	app['Foo']
to
	app.Foo

Also makes static analyzers able to detect invalid attributes as the set
is now limited in the class definition.

As a bonus, setting of the default field values is now done in the
constructor, not separately and manually.

tests/common.TestCase

@@ -116,8 +116,8 @@ class CommonTest(unittest.TestCase):
         config['sdk_path'] = os.getenv('ANDROID_HOME')
         config['build_tools'] = 'FAKE_BUILD_TOOLS_VERSION'
         fdroidserver.common.config = config
-        app = dict()
-        app['id'] = 'org.fdroid.froid'
+        app = fdroidserver.metadata.App()
+        app.id = 'org.fdroid.froid'
         build = dict(fdroidserver.metadata.flag_defaults)
         build['commit'] = 'master'
         build['forceversion'] = True

tests/import.TestCase

@@ -30,12 +30,12 @@ class ImportTest(unittest.TestCase):
         fdroidserver.common.config['sdk_path'] = '/fake/path/to/android-sdk'
 
         url = 'https://gitlab.com/fdroid/fdroidclient'
-        appid, app = fdroidserver.metadata.get_default_app_info()
-        app['Update Check Mode'] = "Tags"
+        app = fdroidserver.metadata.get_default_app_info()
+        app.UpdateCheckMode = "Tags"
         root_dir, src_dir = import_proxy.get_metadata_from_url(app, url)
-        self.assertEquals(app['Repo Type'], 'git')
-        self.assertEquals(app['Web Site'], 'https://gitlab.com/fdroid/fdroidclient')
-        self.assertEquals(app['Repo'], 'https://gitlab.com/fdroid/fdroidclient.git')
+        self.assertEquals(app.RepoType, 'git')
+        self.assertEquals(app.WebSite, 'https://gitlab.com/fdroid/fdroidclient')
+        self.assertEquals(app.Repo, 'https://gitlab.com/fdroid/fdroidclient.git')
 
 
 if __name__ == "__main__":

tests/metadata.TestCase

@@ -39,10 +39,15 @@ class MetadataTest(unittest.TestCase):
 
         apps = fdroidserver.metadata.read_metadata(xref=True)
         for appid in ('org.smssecure.smssecure', 'org.adaway', 'net.osmand.plus', 'org.videolan.vlc'):
-            with open(os.path.join('metadata', appid + '.pickle'), 'r') as f:
+            app = apps[appid]
+            savepath = os.path.join('metadata', appid + '.pickle')
+            self.assertTrue(appid in apps)
+            with open(savepath, 'r') as f:
                 frompickle = pickle.load(f)
-            self.assertTrue(appid in apps.keys())
-            self.assertEquals(apps[appid], frompickle)
+            frommeta = app.field_dict()
+            self.assertEquals(frommeta, frompickle)
+            # with open(savepath, 'wb') as f:
+            #     pickle.dump(app, f)
 
 
 if __name__ == "__main__":

tests/metadata/net.osmand.plus.pickle

@@ -491,12 +491,16 @@ S'metadata/net.osmand.plus.xml'
 p178
 sS'Disabled'
 p179
-NsS'Update Check Name'
+NsS'added'
 p180
-NsS'Vercode Operation'
+NsS'lastupdated'
 p181
-NsS'Current Version'
+NsS'Update Check Name'
 p182
-S'1.9.5'
+NsS'Vercode Operation'
 p183
+NsS'Current Version'
+p184
+S'1.9.5'
+p185
 s.

tests/metadata/org.adaway.pickle

@@ -2290,4 +2290,8 @@ NsS'Update Check Name'
 p483
 NsS'Vercode Operation'
 p484
-Ns.
+NsS'added'
+p485
+NsS'lastupdated'
+p486
+Ns.

tests/metadata/org.smssecure.smssecure.pickle

@@ -772,4 +772,8 @@ NsS'Update Check Name'
 p227
 NsS'Vercode Operation'
 p228
-Ns.
+NsS'added'
+p229
+NsS'lastupdated'
+p230
+Ns.

tests/metadata/org.videolan.vlc.pickle

@@ -5610,14 +5610,18 @@ S'metadata/org.videolan.vlc.yaml'
 p1519
 sS'Disabled'
 p1520
-NsS'Update Check Name'
+NsS'added'
 p1521
-NsS'Vercode Operation'
+NsS'lastupdated'
 p1522
-S'%c + 5'
+NsS'Update Check Name'
 p1523
-sS'Current Version'
+NsS'Vercode Operation'
 p1524
-S'1.2.6'
+S'%c + 5'
 p1525
+sS'Current Version'
+p1526
+S'1.2.6'
+p1527
 s.