fix(waitFor): waitFor should not overwrite implicitWait globally

Before this fix, waitFor was setting implicitWait for the whole
session.

We now set it back to the default.

A better approach would be to set it back to what it was previously.

I do not need this atm.
Merge pull request #168 from camme/fix-waitFor-command

fix(waitFor): waitFor should not overwrite implicitWait globally