Pipe script keywords and restful improvements

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0.0.12:

• Adding assert keyword (PipeScript should support assert #143)
• Fixing new keyword for blank constructors (new keyword should pass null when no argument-free constructors are found. #142 )
• Rest Transpiler:
  • Handling multiple QueryString values (REST transpiler should join query strings with multiple values #139)
  • Only passing ContentType to invoker if invoker supports it (REST transpiler should only pass down ContentType if supported by Invoker #141)
  • Defaulting to JSON body when ContentType is unspecified (REST transpiler should default to JSON for body when content type is unspecified. #140)