Fix for issue 92

Added a few tests for Boulder County data that surfaces the bug reported in issue #92. 
Tests proved issue was in make_name_trails (renamed to make_named_trails).
Read up on groupby (https://docs.python.org/2/library/itertools.html#itertools.groupby) and saw "Generally, the iterable needs to already be sorted on the same key function." so added a sort to make_named_trails. Viola. All better now.