#137 added guard clauses
installed LiteGuard.Source package into ScriptCs.Core only and linked from other projects
created ScriptCs.ruleset based on MS recommended rules and added CA1062: Validate arguments of public methods
Merge pull request #242 from adamralph/137-guard-clauses

#137 added guard clauses
Bump the version to v0.5.0-alpha
Respect the allowPreRelease flag even if no version is provided
Merge pull request #254 from jrusbatch/issues/252

Allow installation of prerelease packages without requiring a valid version to be specified.
Adding a filter for non-managed assemblies
Moving non-managed file detection into the IScriptCommand implementations
Adding abstraction on the AssemblyName API
Refactoring IAssemblyName to IAssembly
Adding implementation for IAssembly interface and adding it to IoC
Implementing a unit test for non-managed assemblies
Merge branch 'non-managed-dlls' of github.com:aaronpowell/scriptcs into non-managed-dlls