Add missing parameter to documentation
Add ability to merge all found instances of nfs::mounts in Hiera.

This patch uses hiera_hash to find all instances of nfs::mounts. The
default for this is false, to preserve backward compatibility, but will
change to true in future versions.
Fix Travis to work with ruby 1.8.7

https://github.com/bundler/bundler/issues/2784
Test against Puppet v3.4.2 with Travis, though let it fail
Merge pull request #21 from ghoneycutt/330_support_merge_hash

support merge hash