Have the build system insert the STABLE constant rather than humans.

Humans are fallible, and our previous tests to make sure that stable
branches had the stable build symbol defined were flawed.

This change has the `bin/build` code insert the `STABLE` constant
automatically if we're on the appropriate branch.

This also removes the test that wasn't ever realising that our
previously defined stable symbols were commented out.

Happily tested by me.
bin/build: Options should be empty when not on stable
Merge branch 'release-v1.2' into moar_stable

* release-v1.2:
  Allows removal of multiple mods
  CmdLine: Tweaked message displayed on download failure.
  Re-catches DownloadErrorsKraken
  Tests: Discussed RelationshipResolver behaviour with installed mods.
  Fixed issues with pull request. Re-added if null check - removed by mistake. Added test to check this code. Removed Service in Tests.csproj
  Fixed bug and added more tests. Bus was in "sub_options = options". I assume the RROptions was a struct at some point?
  Adding basic tests to RealationshipResolver.
  Nunit requires public accessibility for testcases.
  Started work on a random module generator to aid in testing. Added a online category to some tests which require online access. Saved a copy of CKAN-meta-testkan.zip so that the sanity checker tests are offline. Fixed KSP.Training test to work on windows as well as linux. Moved tests in CKAN folder to match files in code.
  Have our build system actually include the icon.
  Transparent icons, larger range of sizes.
  Add a CKAN icon.

Conflicts:
	CKAN/CmdLine/CmdLine.csproj
	CKAN/GUI/CKAN-GUI.csproj
	bin/build
	bin/build.lean
Merge pull request #546 from pjf/moar_stable

Have the build system insert the STABLE constant rather than humans.