Add riak test for truncated schema

If a schema is truncated then a 400 should be returned to the client.
Protect against truncated schemas

Parse schema before storing and return error tuple if it fails to
parse.  Return 400 for HTTP interface.
Auto-add yz fields and uniqueKey

Automatically add the schema config needed for Yokozuna to function
correctly.  This will mutate the user's schema, stripping comments,
changing whitespace in some places, and redifining `uniqueKey`.  For
this reason I wonder if it would be better to simply reject
non-conforming schemas and let the user copy/paste the necessary
config.
Verify schema

Rather than silently mutating the user's schema verify that certain
configuration is present or return an error otherwise.
Remove unused schema xform code
Add _yz_str field type

Use a dedicated field type for yz fields so that users are free to
define their own `string` field type.
Add more schema admin tests

* confirm 400 on  missing yz fields
* confirm 400 on bad uniqueKey
* confirm 400 on bad _yz field
* confirm 204 on default schema
Fix delete-by-id bug

When doing a delete-by-id Solr uses the mnemonic `id` to stand for the
`uniqueKey`.  That is, even if `uniqueKey` is not `id` you still pass
in `id` as the field name to delete-by-id.
Fix --test arg for verify script

Don't delete the `yz_rt.beam` file as it holds common functions for
all riak tests.
Make use of yz_rt where possible

Change some of the tests to use common functions in yz_rt.
Merge pull request #89 from basho/rz-verify-schema

basic schema validation