Remove catch from test

The `should_copy_update_test` occasionally fails but the catch is
covering up the reason for failure.  Remove the catch and investiage
the occasional failure later.
Add bad schema test

Add a test that uploads a schema with a bad classname.  This will
cause the Solr Core CREATE call to fail which will cause an exception
to be thrown in yokozuna eventually leading to the death of the
cluster.

The next commit will protect Yokozuna from crashing in this case.
Don't crash on bad schema

It is fairly easy to create a schema that will cause a runtime error
in Solr when trying to create the core.  Currently Yokozuna causes the
entire cluster to shutdown in this scenario because yz_events reaches
max restart attempts.  This patch makes index creation a best effort.
It will periodically retry.  If the schema is bad the user can upload
a new one which will be used on the next retry.  The riak and solr
logs will be loud about failure and should have enough info to correct
the problem.
Handle error from `yz_solr:cores`

The `remove_non_owned_data` function is run on every `yz_event` tick.
If an error is encountered while getting the list of cores then do no
work and retry on next tick.
Fix `yz_solr:delete` spec
Merge pull request #93 from basho/rz-schema-crash

protect against bad schemas