Tests: added tests for translating $dollar into a literal $.
Tests: added tests for translating $dollar into a literal $.

If you need to specify a $ in a URI you can now use '$dollar' or
'${dollar}'.

Added some tests for the above to test_variables.py setting a Location
string.

nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit