SCHEMA-177. Fixes NPE in AuthorityParser.

NullPointerException arising from null String parametrized
AuthorityParser replaced by a formal KijiURIException
detailing the issue. Also added a unit test and edited some
KijiURIException messages. Exception messages thrown by
resolve() updated.
KIJIMR-58. Space-separated map parser.

Signed-off-by: Lee Sheng <lsheng@wibidata.com>