Adding .NET Support

This patch adds .NET/ASPX language detection to
the lp-cedarish language pack. To use this, a
source repo needs a .sln file.

With a valid .sln file, the language will be
detected, and the Mono runtime requirements
downloaded, and used by the slugbuilder.

fixes-bug 1319406

Change-Id: I4dbbe6bedf2ea20df8c25df18ea21c66a869a279