Add pyyaml to requirements.txt
Remove the need for image files in tests.

We use the python unittest class methods to setup the images so they are not
called for every test.
* tests/helpers.py : We add an additional image to the image list
"2013_10_30_06_30_00".
(imgs_common_tsdir): New method that will setup and tear down all images
necessary for the tests
* tests/test_classes.py (TestTimeStreamStr, TestTimeStreamLoad)
(TestTimeStreamImagePathAssing, TestTimeStreamIterByFiles)
(TestTimeStreamIterByTimepoints): Add setUpClass and tearDownClass
class methods.
* tests/test_parse.py (TestAllFilesWithExt, TestGuessManifest, TestGetImage):
Likewise
Fix bugs and warnings in ts.manip.pot

* timestream/manipulate/pot.py: rm unused import of cv2, fix variable
	naming/typo bug, fix 'not x in y' => 'x not in y'
Merge pull request #153 from Joelgranados/testnoimg

Remove the need for image files in tests.
Merge pull request #155 from kdmurray91/fix/misc_warnings

Fix bugs and warnings
Merge pull request #156 from kdmurray91/joelnext

Joel's latest changes
Trap import of PyQT4; allow headless pipeline runs

Here, we trap import PyQT4 in a try except block, and move all
GUI-specifc stuff to a separate file.

* scripts/_pipeline_gui.iu: (NEW) rename UI file
* scripts/_pipeline_gui.py: (NEW) Move all UI code to a new module
* scripts/run_pipeline.py trap importing PyQT4 so we can still run CLI
  pipelines without it installed.
A better version of the GUI/CLI seperation

Now, we have one script for the gui, pipeline_gui.py, and one for the
CLI and common code, run_pipeline.py

* scripts/_pipeline_gui.py -> scripts/pipeline_gui.py (rename) also
  import common stuff from run_pipeline.py
* scripts/_pipeline_gui.iu -> scripts/pipeline_gui.ui (fix renamingtypo)
* scripts/run_pipeline.py: Move all GUI stuff to pipeline_gui.py