Add support for PS v2

Fixes https://github.com/tkellogg/Jump-Location/issues/21

By using the alias 'ModuleToProcess' for 'RootModule' as well as renaming
load.ps1 to have extension .psm1, which is the appropriate extension for
powershell modules, jump-location is now backwards compatible with
Powershell V2.
Please, also update: .csproj file, copyBuild.ps1 file. Now project cannot be build