Fix issue where NuGet server returned for FindPackagesById()? a page with a list of entries each with a different version.

Before this commit Paket was just considering the version in the first entry.
Only generate XML for used packages
small cleanup
Merge pull request #393 from jvrdev/master

Bugfix: several version entries in current page
Merge branch 'master' of https://github.com/fsprojects/Paket
RELEASE_NOTES
Fix issue where NuGet server returned for FindPackagesById()? a page with a list of entries each with a different version.

Before this commit Paket was just considering the version in the first entry.
RELEASE_NOTES
Bump version to 0.16.2
Merge branch 'bugfix'

Conflicts:
	RELEASE_NOTES.md
	src/Paket.Bootstrapper/Properties/AssemblyInfo.cs
	src/Paket.Core/AssemblyInfo.fs
	src/Paket/AssemblyInfo.fs
Use ToString for Domain concepts
small cleanups
Don't use Dictionary for usedPackages.
small cleanup
Refactor NuGetV2.followODataLink to take a function to get the url contents so that a stub can be injected for testing.
Add regression test for https://github.com/fsprojects/Paket/pull/393

Cosmetic changes within NuGetV2.fs
Only delete custom nodes that are contained in model
RELEASE_NOTES
Merge pull request #397 from jvrdev/master

Regression test for https://github.com/fsprojects/Paket/pull/393
RELEASE_NOTES