Update FileProxy.js

Handle an encoding error
CB-6940: context.getExternal* methods return null if sdcard isn't in mounted state, causing exceptions that prevent startup from reaching readystate

Signed-off-by: Joe Bowser <bowserj@apache.org>
CB-6940: Android: cleanup try/catch exception handling

Signed-off-by: Joe Bowser <bowserj@apache.org>
CB-6940: Fixing up commit from dzeims
Merge branch 'patch-1' of https://github.com/TNKSoftware/cordova-plugin-file
Cleanup pull-reqs. This closes #34