Fixing JNI issue when larget dataset is used and some other changes

This commit includes couple of changes and fixes. Last time, I added a new feautre in featConvertor.py and I noticed that i made a typo error in the help section. Also the overloading of functions was giving error for somereason so I changed the function name to allow generating Xte.libsvm without hassle. 

Secondly, major work involves fixing error "JNI ERROR (app bug): local reference table overflow (max=512)" when I tried to use a subset of my csv dataset with 500 rows even. I made changes in Manifest.xml and AndroidJNI_source.cpp which has the main fixes. I also added some new flags in Android.mk and Application.mk for better execution and debug mode in C/C++.