Merge pull request #174 from GXV738/gxv738_dev

Sensor and ScreenOrientation
Signature: remove from rhoelements app
Doc: fix Android Google Map instructions
updated descriptions in network xml
Merge branch 'master' of https://github.com/rhomobile/rhodes
wm: return Camera and Signature Rhodes API
restore old Camera and Signature on iOS
Fix build at win XP. Call external command at build run only.
Fixed the issue where sensor events were not reaching the JS/Ruby callback
Merge branch 'master' into gxv738_dev