add frontend submodule

* configure cross-building for scala 2.10 and 2.11
* fix meta compilation for scala 2.11
* assembly all build settings in single Build.scala file
Merge branch 'frontend' into 'master'

Frontend

* configure `core` project cross-building for scala 2.10 and 2.11
* fix `core` compilation for scala 2.11
* assembly all build settings in single Build.scala file
add how to build frontend
add project template
Update sbt-assembly
add simple transformer
DependentCompileTests replaced with 'Boilerplate Test' build config in TeamCity
Fixed a failing test
Restore fork in meta/test
add test for values
Merge branch 'frontend' into 'master'

Frontend

It is a minimal example of `Yin-Yang` integration to `scalan`.

!!! It also adds some modifications to the project build. This change simplifies (a lot) cross-building between different scala versions, and it is the major intent for pull request. After we merge this, I can configure Teamcity build.
Fork in meta/run (needed on TeamCity)
Added push-github script