jack2 supports android devices & rebase current changes to master

Dear all,

I did upload changes for 'JACK Audio Connection Kit for Android' which project is currently maintained on https://github.com/KimJeongYeon/jack2_android.

Feature:
 - runs on latest android's KitKat 4.4.2 platform
 - These changes based on latest jack2 master branch
 - support both ALSA and OpenSLES driver
 - support emulator
 - additionally, some compiler warnings fixed together.

These changes were rebased on latest jack2 master branch, and tested on android's real target & emulator(KitKat ver.).
I hope you review codes or feedback anytime.

Regards,
KimJeongYeon