Fix null instruments
Merge pull request #1136 from bootstraponline/fix_null_instruments

Fix null instruments
Catch exception

command.getElement() may return null. Appium must catch exception or it'll crash with a NullPointerException.

Fix #1140
fix steps and duration logic for swipe and flick
Merge pull request #1145 from bootstraponline/catch_exception

Catch exception
Merge pull request #1152 from jlipps/master

fix android swipe duration