Added test cases for single quoted strings, both forms of triple quotes,  and some string concatenations. Removed unneeded __future__ print_function import.
Added test cases for single quoted strings, both forms of triple quotes,
 and some string concatenations.
Removed unneeded __future__ print_function import.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator