Refactors speclj Leiningen task and speclj.main.

Instead of launching a new JVM to run tests, run the tests in the leiningen JVM. On my machine, this patch
decreases the amount of time to run `lein spec` from 6 secs down to 3
secs for the speclj test suite.
Merge pull request #67 from mylesmegyesi/run-spec-task-in-project

Refactors speclj Leiningen task and speclj.main.