Add favicon. Fixes https://github.com/sympy/planet.sympy.org/issues/6
Merge pull request #22 from debugger22/master

Add favicon.
Add sympy_favicon.png to config.ini and reduce the size of favicon
Merge pull request #24 from debugger22/favicon_fix

Add sympy_favicon.png to config.ini and reduce the size of favicon
Revert "Add sympy_favicon.png to config.ini and reduce the size of favicon"

This reverts commit 667e11420ecf8ea0655c7b24dfc3085fe5706120.

@asmeurer gave it -1 here: https://github.com/sympy/planet.sympy.org/pull/24#issuecomment-41513458
Add favicon file to config.ini