2.50.0

Experimental Visual C++ support - #1467
BUGFIX: Install packages that end in .dll - #1466
BUGFIX: Prevent race condition - #1460
BUGFIX: Download of HTTP dependencies should delete folder before we unzip
BUGFIX: Do not touch project files in packages folder - #1455
BUGFIX: Keep versions locked for dependencies during pack - #1457
BUGFIX: Do not fail on auth check for remote dependencies file - #1456
WORKAROUND: Don't use v3 getPackageDetails on nuget.org or myget