Merge pull request #5 from goedman/Stan-j0.3-v0.0.3

Stan j0.3 v0.0.3
Updated README.md and REQUIRE (removed dependency on DataFrames). Ready to bump the tag.
Removed handling of NaNs in input data.
Merge pull request #6 from goedman/master

Synced branch Stan-j0.3-v0.0.3 with tagged master.