Add elseImpersonating and notImpersonating blade directives

[ChrisToxz]

This PR adds 3 new blade directives.

@impersonating and @endImpersonating already exists, but was missing an else statement.
This PR introduces @elseImpersonating .
You can now do:

@impersonating
     Exit impersonating
@elseImpersonating
    Start impersonating
@endImpersonating

This PR also adds @notImpersonating and @endNotImpersonating

@notImpersonating
     Start impersonating
@endNotImpersonating

As suggested in #76 hereby the PR with tests.