Reimplement load_instance_from_solr
Merge pull request #474 from projecthydra/load_from_solr

Reimplement load_instance_from_solr
Waiting on fixes in ActiveTriples

The master branch of ActiveTriples is in flux and needs some changes
before we can use it.  We’re pining to the last known working commit.
Provide a sensible default for base_path
This ensures that we don't encounter
`no implicit conversion of nil into String`
if the value is not set in the fedora.yml