Cleanup properties

Here is a short list of possible properties for the dotnet plugin:

• dotnet.tool.version
• rebuild
• visual.test.project.pattern
• msbuild.configurations
• maven.dotnet.disable.postbuild.event

Please use always the same convention.
Because a lot of maven.* properties already exists (maven.compiler.debug), I think that the best conventions is:

• maven.dotnet.tool.version
• maven.dotnet.rebuild
• maven.dotnet.test.project.pattern
• maven.dotnet.msbuild.configurations
• maven.dotnet.disable.postbuild.event