NET40 vs NET45

- NET45 is the default, with NET40 generated off of it using plain xslt.
- nuspecs now include NET40 too.
- Async is excluded for now since it's still written in a NET45
(async/await fashion).
- Need to do some housekeeping since some things from my NET20/35
attempt are still lingering.
Merged with master
NET40 wants more

- Content projects now get a NET40 counterpart
- Excluded the async bits from NET40 for now
- Integrated into the build process.
Adjusted release notes
Heavenly Father

- Blasphemy! Forgot about a file conflict that accidently go committed
- Updated packages, adjusted nuspecs, pray this works (need some tests
to make sure the nuspec deps are in sync with the proj deps)