Ensure we have boost 1.48 when building on travis.
Add gfortran to the travis dependencies.
Inform configure script where llvm is when running on travis.
Allow parallelism (-j 2) when building and testing on travis.
Work around travis' 10 minute timeout.
More travis fixes...
Extend the travis timeout to 60 minutes.
Reformat .travis.yml for easier merging.
Remove the llvm dependencies that were included when cherry-picking from
the cxxr-jit branch from the travis configuration.
Downgrade boost requirement from 1.53 to 1.48

Conflicts:
	aclocal.m4
Merge branch 'master' into cxxr-jit

Conflicts:
	.travis.yml