update for time::at_utc API change: handle Err()

ref:

84ce372ceec5322f8bfef82367e03bd7a4de3184 Sep 22 libtime: `strftime` and `strptime` return type changed to `Result<String, ParseError>`.
Merge pull request #5 from jgallagher/open-str-ref

Have access::open take a &str instead of a String
Use `warn(missing_doc)` to bring documentation to a level of completion.
  - in lib example, demonstrate column lookup by name
  - allow(missing_doc) for mod ffi, Sqlite enum values
  - add TODO re lifetime in impl RowIndex for &str
  - mark APIs with TODOs as #[unstable]
Rename fail! to panic!
Rename missing_doc to missing_docs
Rename unused_variable to unused_variables
Merge pull request #12 from gwenn/fail_panic

Rename fail! to panic!