Fixing merge issue
Add logics to pick the portable framework folder than has the most matching platforms when installing into a portable project.
Merge branch '2.1'
Caching package sources to work around crypto error
Work Item: 2345
Updating minor version and build number
Modifying Debug build to work with VS 2012 if available
Do not accept web.{configurationName}.config.transform in non-web projects. Work items: 2550
Merge branch '2.1'
Ensure base path when building a package from a project is set to project
root.

Work Item: 2588
Ensure safe updating a package does not leave the dependency chain
uninstalled.
Work item: 2569
Fix incorrect behavior when choosing between client and full profile framework folders. Work items: 2502
Support creating empty folders from .nuspec
Add FindPackagesById service method to LocalPackageRepository
Work Item: 2387
When packing package from a project with a nuspec file, do not include content files if the nuspec file specify the <files> element. Work items: 2575
Fix issue 2597:
- Inject project properties in ctor of Project type so any conditional imports that rely on them are resolved correctly.
- When resolving the path, only add properties to project that aren't already global properties of the project (those injected in the ctor).
- Changed Properties property name to ProjectProperties to avoid ambiguity between Project properties and Package properties.
Added comments & unit test for fix of issue 2597
Merge branch '2.1'
NuGet.exe install fails to install a new version of a package when
-ExcludeVersion flag is specified.

Work Item: 2578
Bootstrapper should return exit code of NuGet.exe

Work Item: 2584
Adding NuGet.Build to solution