Throw when routes are empty or malformed

[tptee]

Adds some basic sanity checks for route configurations passed in to the store enhancer. Throws errors with some informational messages when the routes are empty or malformed (e.g. they don't all start with a slash).

/cc @baer @kriuz

[coveralls]

Coverage increased (+0.07%) to 98.374% when pulling ec59e34 on chore/throw-on-no-routes into e2aa438 on master.

[coveralls]

Coverage increased (+0.07%) to 98.374% when pulling ec59e34 on chore/throw-on-no-routes into e2aa438 on master.

[jondelga]

Looks great, this should be helpful.