Changed routes to be more sane.
Add type signatures to things in Foundation.hs.
Improve key generation, fix compile warnings.

I fixed the `genKey` function in Foundation.hs so that
* It now accepts an integer argument pertaining to the length of the key.
* The keys are alphanumeric.

All of the compile warnings I fixed came from Handler/CreateAccount.hs. They
were mostly about overshadowed bindings and implicitly typed expressions.

The key generation now uses maps, hence the dependency on "containers".