Update CONTRIBUTING.md

Updated CONTRIBUTING.md to specify that the `this` keyword should be avoided.
Fixes #35: Solution file should be located in the root of the repository
refactored roslyn out of core to fix #90 in preperation for #80
refactored roslyn out of core to fix #90 in preperation for #80
Update README.md
Update README.md
Add missing content to common assembly info files
Add a description to the ScriptCs.Core assembly
Add a description for the command line application
Add nuspec files for ScriptCs.Core and ScriptCs.Contracts
License URL should point to LICENSE.md in the master branch of the repository
Add missing Build.tasks file
# Updated code base to get rid of MEF attributes and use RegistrationBuilder
refactored code to bring ScriptPackSession back into the core

1. We refactor ScriptPackSession so it is just a data bag with some
methods.
2. That allows it to be easily passed to the engine which figures out
how to apply it.
3. We move the initialize and terminate into ScriptCs.core.
added [InheritedExport] back onto IScriptEngine
# Removed namespaces that are no longer used
# Simplified code for IScriptEngine constructor convention. Thanks to @khellang for the code review.
Merge branch 'dev' into regbuilder
Add packaging targets to build script
moved ScriptHostFactory into Roslyn since the script host is Roslyn specific