Added date stamp of RMG job to chemkin file.
Incorrect case usage in DASPK Makefile fix.

Remember that Makefiles are case-sensitive...
Typo in kinetics database for cyclic ether formation.
Update copyright in license to 2013.
Update documentation version references to 4.0 for the new release.
Update RMG credits to include new developers.
Updated documentation example condition files page to include sulfur
and liquid oxidation examples.
Added `Tips for Setting up a RMG Job` page to documentation.
Removed deprecated Sulfur database.
Revised `Tips for Setting up an RMG Job.`
Adjusted A factor in H_Abstraction rule #75.

The previous A-factor was orders of magnitude larger than other A-factors
from the Saeys rules. We attempted to use the Saeys group values to
estimate the correct value, and got a number far closer to 3e12 than
3e18. This is also much more consistent with an estimate from Tsang (in
the NIST database).