Fix find_elements :id on Android

Don't error when there are no ids. Return an empty array.

Fix #1167
Merge pull request #1170 from bootstraponline/android_ids_fix

Fix find_elements :id on Android
Added variable camelCasing to style guide.
Merge pull request #1175 from filmaj/style-guide-camelCase

Added variable camelCasing to style guide.
Update clean.apk

Fix min sdk version
Fix account removal logic
Merge pull request #1176 from bootstraponline/master

Update clean.apk
Update Android Touchevent for long press

This long press code supports only for iOS application. So I am updating the Android Touchevent for long press.
Update troubleshooting.md

Updated troubleshooting for 'Webview/Hybrid/Safari app support'
Merge pull request #1178 from mgmanikandan87/patch-1

Update Android Touchevent for long press
Merge pull request #1179 from PavithraNavaneeth/patch-1

Update troubleshooting.md
Fix warning
Merge pull request #1184 from bootstraponline/master

Fix warning
Robust, device-friendly unlock. Added gitsubmodule for unlock_apk.
reset.sh now builds the apk. adbs unlockScreen method now invokes
unlock.apk. added a new small, focused module called device_state to handle determining state of emulators/devices. currently has a "isScreenLocked" function. unlockScreen in adb.js now 1) checks if screen is locked or not first before doing anything and 2) uses unlock.apk to do the unlocking.
Code snippet for long press in Android Touchevent (Java and Python)

Updating python script for longclick  touchevent in android.
Merge pull request #1186 from mgmanikandan87/patch-2

Code snippet for long press in Android Touchevent (Java and Python)
increasing instruments timeout
Merge pull request #1190 from prolificcoder/master

increasing instruments timeout
Update hybrid.md

Added ruby syntax
Merge pull request #1193 from feelobot/patch-1

Update hybrid.md
Fixes from code review on #1161