Use gradle script to simple compile

[TakumaLee]

Reference: https://www.virag.si/2015/01/publishing-gradle-android-library-to-jcenter/

I changed .gitignore to avoid some build files and added gradle scripts to publish library to jcenter. Would you please modify build.gradle in Simple Facebook like below

developer { // #CONFIG# Change to Your information
                        id 'takumalee'
                        name 'takumalee'
                        email 'vmgsahm1@gmail.com'
}

Because it is easier to use by just adding one line,

e.g.

compile 'com.sromku.simplefacebook:SimpleFacebook:1.0.0'