Fix building error with 1.9.3

The commit 96802e9b0de4 forgot to add coding statements at the very
top of the file. This commit fix the test suite for 1.9.3 which failed
on both MRI and Rubinius.
Add MRI 2.0.0 to the Travis matrix
Remove RDiscount from the benchmark suite

Since RDiscount isn't supported on 1.9.2, we can remove it from
the benchmarks to ensure Redcarpet is compatible with 1.9.2
Merge pull request #249 from vmg/travis-suite

Fix building errors