Update __init__.py

updated keywords to correctly use json fields
Update __init__.py

forgot to update keyword press_back_button with json approach
Update __init__.py

Added new argument test_server_port to start the test_server
Update __init__.py

more compatibility fix for calabash-android 0.4.x
Update __init__.py

added support for http_proxy in the Start Emulator keyword
Update README.rst

updated compatible calabash-android version
Update to improve compatibility with older version

made change suggested by @bogensberger
Now it was really updated :)
Bad copy-and-paste. this version should be ok.
Corrected implementation for json detection

The detection should be done using a try/catch :S
Merge pull request #62 from caio2k/master

keywords compabitility update for json and added argument to start test_server on calabash-android 0.4.18