Updated to 1.4.0.74 (latest) of MSBuild.Community.Tasks.

Removed the files tag from the nuspec - this makes the package an 'external package' (as it has content) and means other external packages (i.e. most Chocolatey packages) can depend on it without hitting this problem: http://nuget.codeplex.com/workitem/595.
Included LoreSoft's copyright statement (see https://github.com/loresoft/msbuildtasks).