Utility updates

Highlights:
* Add `Makefile.config.ubuntu1404cpu` for Linux CPU network testing
* Add `python/convert_image_mean_to_mat.py` to convert an image mean `binaryproto` file to a Matlab file for debugging (some of this could potentially be merged into `python/caffe/io.py`)
* Aesthetic improvements to `python/examine_leveldb.py`, and add option to save dumped images in subfolders by label
* `python/caffe/draw.py`: PRETTY COLORS!!!
* Python log parser in `tools/extra/parse_log.py`; required some decomposition in `tools/extra/extract_seconds.py`. Parser for old log files (before the log format changed) added as `tools/extra/parse_log_old.sh`
* Update `tools/extra/plot_training_log.py` to work with the python log parser, but in a dumb way. In the future, it should use it as a library, not as a system command.