Use run_on_modifications instead of run_on_changes
Don't run tests from run_on_additions

Adding a file triggers run_on_modifications which runs the tests. It is
therefore unnecessary to run the tests from run_on_additions.
Match EOL within expressions in Guardfile template
Match EOL in Guardfile expressions
Add EOL characters to expressions in README
Add ruby 2.1 to Travis CI
Merge pull request #99 from mgarriott/match_eol_in_guardfile

Explicitly match end-of-line characters in Guardfile expressions
Merge pull request #102 from deivid-rodriguez/add_2_1_to_travis

Add ruby 2.1 to Travis CI
Merge pull request #98 from mgarriott/prevent_tests_running_multiple_times

Prevent tests running multiple times