Jupyterthemes

- fixed hbox widget display (no longer vertically stacks objects)
- applied style to pager documentation
- added gridlines option to jtplot.style() to set linestyle of axis grid
- README update with more jtplot documentation
- removed seaborn from dependencies
- explicitly import stylefx and jtplot modules to \__init__.py

- minor bug-fix in jtplot (prevent clist printing)

- improved monokai comment visibility
- solarized style improvements (l & d flavors)
- improved kernel-busy animation
- moved kernel-idle/busy code from extras.less to notebook.less
- notebook-fontsize (-nfs) adjusts header
- minor cosmetic improvements
- fixed matplotlib error in jtplot
- added check_dependencies() fx to prevent unnecessary dependency installs

- fixed pulse kernel-busy indicator

- removed broken matplotlib dependency
- added pulse kernel-busy indicator

- added matplotlib and seaborn dependencies
- updated index.ipynb for binder and compiled themes
- minor cosmetic improvements