Add missing store parameter, and remove warning.

Some functions were not passing through the store parameter, but
accidentally relying on the thread-bound *store* instead.

Also, removed warning for replacing "list" from clojure.core. It turns
out that doing this actually causes a NPE when compiling (eg: lein
uberjar) a project that depends on clojure-mail.
Merge pull request #18 from RallySoftware/master

Add missing store parameter, and remove warning.