S3: Qualify DataSource paths

Impala qualifies all paths stored in the metastore except for the
DataSource jar path.  Use a qualified path here as well, which will
allow datasources to live on the non-default FS.

In CreateDataSrcStmt, use the post-analyzed qualified path rather than
the user passed string.  Then, fix CreateTableDataSrcStmt so that it
doesn't strip out the scheme://authority portion of the URI, but instead
uses the qualified path string directly.

Note that the metastore may still contain unqualified paths in
DataSource tables' properties that were generated by previous versions.
That's okay though since the backend won't assume all paths are
qualified in case other components generate (or have in the past)
metadata with unqualified paths.

Change-Id: I905d8f6a7bf1793cfccf720b6ab5dc845d7dd5fa
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/5201
Reviewed-by: Daniel Hecht <dhecht@cloudera.com>
Tested-by: jenkins