dscanner - Drozer based post-build dynamic vulnerability scanner command

* New command `dscanner`, enables one to scan signed APKs with Drozer
 * Drozer is a dynamic vulnerability scanner for Android
 * Drozer runs in a emulator or on-device, this new `dscanner` command...
  * starts a docker image with Drozer and the Android Emulator pre-installed,
  * loads the signed APK into the emulator
  * activates Drozer automated tests for the APK
  * gathers the report output and places it next to the original APK
 * The Drozer docker image can be:
  * cached locally for re-use (just don't run --clean*)
  * retrieved from dockerhub.com for more efficient runtime
  * or be built from scratch (in the new "./docker" directory)
 * New "Vulnerability Scanning" documentation section (run gendocs.sh)

README.md

@@ -76,3 +76,19 @@ Then here's how to install:
 	source env/bin/activate
 	pip3 install -e .
 	python3 setup.py install
+
+
+### Drozer Scanner
+
+There is a new feature under development that can scan any APK in a
+repo, or any build, using Drozer.  Drozer is a dynamic exploit
+scanner, it runs an app in the emulator and runs known exploits on it.
+
+This setup requires specific versions of two Python modules:
+_docker-py_ 1.9.0 and _requests_ older than 2.11.  Other versions
+might cause the docker-py connection to break with the containers.
+Newer versions of docker-py might have this fixed already.
+
+For Debian based distributions:
+
+	apt-get install libffi-dev libssl-dev python-docker