cache compiled result

[lingyan]

Optimize performance by caching the compiled route paths.

@mridgway cc: @jasisk

[yahoocla]

CLA is valid!

[coveralls]

Coverage remained the same at 100.0% when pulling 842ecdd on cacheCompiled into 97d14ff on master.

[redonkulus]

👍

[mridgway]

👍

[coveralls]

Coverage remained the same at 100.0% when pulling 4e94f23 on cacheCompiled into 97d14ff on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 4e94f23 on cacheCompiled into 97d14ff on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 4e94f23 on cacheCompiled into 97d14ff on master.

[coveralls]

Coverage remained the same at 100.0% when pulling c85506b on cacheCompiled into 97d14ff on master.

[lingyan]

Minor change (added routePath to error message on https://github.com/yahoo/routr/pull/26/files#diff-504fd89f344be1e9c4b583f3ebd7428aL153)