BUG: Do not try to restore old PATH in TubeTKLauncher.bat.

This causes failures on boxes with entries in their path that have
parenthesis, such as "Program Files (x86)".

The PATH does not need to be restored before exitting regardless --
the calling shell does not inherit the value.
Merge pull request #217 from thewtex/windows-failures

BUG: Do not try to restore old PATH in TubeTKLauncher.bat.