Added a bunch of assemblies to tests

Added ScriptCS.Engine.Roslyn and Roslyn.Compilers to make
Auth_CanAddRemoveUsernameToRole and
WhenScriptStringIsRun_ActionRespondsToMessage
Optimized dictionary access in ScriptRunner.cs
Seperated out path in ScriptsTest.cs CanRegisterCompiledScripts() test
to make it easier to debug.