Remove obsolete options

Deprecated in Java 8, apparently removed in 9
Remove unmaintained sbt-android plugin.

This plugin is not needed by any other project in the community build
so it's safe to just remove it.
Remove references to sbt 0.12.x.

They are not needed because sbt 0.13.x is backwards compatible.

Switch to custom fork of sbt-idea plugin. That version of sbt-idea
depends on newer version of sbt-pgp plugin. Newer version has correct
dependencies and fixes the following problem:

[sbt-idea] [error] Modules were resolved with conflicting cross-version suffixes in {file:/localhome/jenkinsdbuild/workspace/Community-2.11.x-Java8/target-0.9.1/extraction/082c36b94bc0dd64110a403174908c48bd1a3558/projects/1beff2840ad3d104b774ff8f785a34e2ccfeccfb/project/}root-1beff2840ad3d104b774ff8f785a34e2ccfeccfb-build:
[sbt-idea] [error]    net.databinder:dispatch-core _2.10, _2.9.1
[sbt-idea] [error]    net.databinder:dispatch-http _2.10, _2.9.1
[sbt-idea] [error]    net.databinder:dispatch-futures _2.10, _2.9.1
[sbt-idea] java.lang.RuntimeException: Conflicting cross-version suffixes in: net.databinder:dispatch-core, net.databinder:dispatch-http, net.databinder:dispatch-futures

We also upgrade to latest release of android-sdk-plugin. This is required as part
of the update of sbt-idea plugin.

Those changes pave the way for resolving #83.
Merge pull request #86 from gkossakowski/java8-driven-cleanups

Java 8 driven cleanups