LatinIME: Add @ character to DE keyboard's more keys

Change-Id: I6a85496e579170a67352160277bfb43125b1e892
Fix LatinIME crashing if JNI lib without gesture support is installed.

Change-Id: I60292a8e272d484e1d4a4407ddceeac863d6d70e
LatinIME: Add fallback loader for JNI lib

Prefer the JNI lib with gesture typing support.
If not available / installed fall back to the standard one without
geture typing.

Change-Id: I70a5f43386a9c72809a70bd286f3702378d6f9be