Testing basic plotting functionality using mpld3

- Added plot method to PCA
- Added example plugin to new package thunder.viz
Added matplotlib and mpld3 to requirements
Added jinja2 dependency
Basic support for plotting via mpld3

- Added a plotting method for PCA that takes turns the analysis results
into an interactive mpld3 visualization
- Three plot types in viz/plots.py
- Colorization options for turning numerical data into colors
Restored toy fish example data
Merge branch 'basic-visualization'