Applying the bintray release plugin

applies the release plugin to following modules :
- core
- pxfetcher

and declares the pxfetcher dependencies on core via mavenCentral because of the multiproject issue with `bintray-release`
![](http://3.bp.blogspot.com/-UdNlffz8C60/U4K7pIP8YDI/AAAAAAAAJ4A/TDwkI9etD9U/s1600/tumblr_mc7kidp4GM1qeh80v-1.gif)

but we want to deprecate it's useage, so write that?