Update CONTRIBUTING.md
new quickstart

updated readme to have an up to date quickstart!
Rewrite README.md
Specify language for syntax highlighting in code blocks
Bump version number to v0.4.0
Merge branch 'master' into dev

* master:
  new quickstart
  Update CONTRIBUTING.md
Merge pull request #247 from scriptcs/dev

Ship v0.4.0
#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.
Refactored FilePreProcessor to remove #r directives and return them in result
Replaced methods with PreProcessorUtil methods. Added tests
Console colors are now properly reset when exiting the REPL.
ExecuteReplCommand should use the implementation of IConsole provided to the ctor
Add test for ExecuteReplCommand.Execute
Added check for existing assembly/script in REPL. Fixes #264
Fixed failing tests and added two more
Merge pull request #263 from jrusbatch/issues/262

ExecuteReplCommand should use IConsole