Added test for when kml.KML.from_string when the string is not a kml (e.g. xml)
Fix typo "lenght" -> "length"
Added pip requirements files and updated README on usage.
Updated travis.yml file to use pip + the requirements/test.txt file
Reverted to older unittest.TestCase.assertRaises form.
This form is compatible with Python 2.6.

Fixes the failures found with Travis builds [53, 54]
Remove "--use-mirrors" argument to pip install (deprecated)
Merge pull request #11 from IanLee1521/master

Fix typo, add pip requirements file, test for kml.KML.from_string when not a kml string
Thanks 8-)