[API] Added a lot of missing implementations required for MVC5+EF6

Conflicts:
	mcs/class/System/System.Net/WebRequest.cs

Conflicts:
	mcs/class/System.Data/System.Data.Common/DbDataReader.cs
	mcs/class/System.Web/System.Web-plainweb-net_4_0.csproj
	mcs/class/System.Web/System.Web-plainweb-net_4_5.csproj
Remove deleted merge file.
Ignore generated files during compile.
Add missing MembershipPasswordAttribute class.

Conflicts:
	mcs/class/System.Web/System.Web-plainweb-net_4_0.csproj
	mcs/class/System.Web/System.Web-plainweb-net_4_5.csproj
Remove unused merge file