Added binder functionality (interactive tutorials online) to documentation

Added links to interactive moose binder environment on main website. See tutorials, 'getting started with python scripting for moose', and the new 'interactive tutorials' tab in quickstart

Addition of Help.png. Related to #225 

Created links to CREDIT and INSTALL  file in README file.

Moved authors/credits to separate file 'CREDITS'.

Documentation update 2

git are converted to pdf in pdf #232.
Using `libertine` font in pdf doc.

Added short hidden section at beginning of cookbook snippet sections explaining how to run the snippets

tweaking pehaps a listing environment for codeblock.
Related to BhallaLab/moose#225 .

* Recovered quickstart section in html, added tutorials placeholder and implemented rudimentary integration between doxygen and sphinx (dependecy on breathe sphinx extension)

* removed recursion limit change

* Added section to quickstart, and fixed a few minor typos in the install page

* Updated installation documentation with new mac osx brew install procedure. Made new section for OSX for consistency of format.

* removed some breathe related stuff from conf.py

* fixed minor typo in wildcard.py

* Recovered rdesigneur tutorial. Modified file by adding extended contents, commented out incomplete sections. Modified rdesigneur snippets page title to 'more rdesigneur examples' instead of just 'Rdesigneur'

* Added autorun statement to Compartment_net.py.

removed pyrun1.py documentation as it is exactly the same as pyrun.py.

updated vec information in quickstart to reflect actual ouput.

* uploaded fixed compartment_net.py without all my comments

* minor changes to install page, changes to doxygen readthedocs generation

* forgot to add hyperlink for doxygen page

* Added Chemical Bistables section to tutorials. Rest incoming

* Chemical Oscillators added, minor tweaks to Chemical Bistables to match Oscillators page

* Deleted extension pyc file as requested by dilawar

* Changed few names, reordered tutorials

* Changes to fix all non-references related and non-snippets related 'make html' errors

* Update crossComptNeuroMesh.py

* Added squid demo to tutorials. Removed squid demo from quickstart. Wrote a bit of theory and history about squid demo. removed redundant modules.rst file.

* Undid changes to loadSbmlmodel.py as it might have caused the mac travis to fail

Added squid demo to tutorials. Removed squid demo from quickstart. Wrote a bit of theory and history about squid demo. removed redundant modules.rst file.