Simplify each BasicTests test.

This extracts the common part of each method into the class constructor and Dispose methods.
Merge pull request #23 from AArnott/TestSimplification

Simplify basic tests
Filter duplicate libraries in GetPackageFiles target
Merge pull request #33 from kovalikp/issue21.v2

Filter duplicate libraries in GetPackageFiles target

This fixes issue 21.
Add .gitattributes to avoid line-ending issues

When using Windows, the best option is to use auto line endings. This
means that git will checkout files using CR/LF and commit as LF.

When installing Git for Windows this is the default, but it's easy for
folks to accidentally override this setting. Thus, it's best to specify
an explicit default at the repository level as this overrules the user
configuration.
Expand .gitignore

We were missing comments and files related to Visual Studio's project
migration backups.
Move package localization to NuPkg helper class
Allow scenario class to take properties
Expose build warnings
Don't build dependencies when building inside the IDE

We don't want to build in case we're performing a design time build
as we are expected to not produce any assets.

We also don't want to build the references in cases where we build
inside the IDE. The reason is that Visual Studio already built our
dependencies. Doing it again can regress performance. However, the
real issue is that it impacts correctness as this can result in
building the same project simultaneously from different projects.

Most particularly on the correctness side, this shows up when VS is
doing a "rebuild". NuProj will end up causing multiple build breaks
being reported because it will re-delete outputs that VS just produced
and that other project references that are building in parallel now
expect to be there.

This fixes issue #13.