Pester testsuite fixed including a fix for issue #122.

The testsuite does not polute the environment-variables and the PSModulePath anymore and the ModuleHash tests avoid issues cause git line ending transformation.

Testsuite was broken at least since merge in commit  fe2cc3f33182e4f384c81e5fb5210c9b6ea174fc.

Testsuite runs in an elevated shell with Powershell v2 and v3.
Merge pull request #134 from flofreud/fix-test-suite

Pester testsuite fixed including a fix for issue #122