Remove improper (and redundant) `:user` deps.

Justification
=============

The dependencies listed in the `:user` profile are the same
dependencies listed for “Lein1”.

We’re *supposed* to leave `:user` outta `project.clj`.
------------------------------------------------------

Using Leiningen 2.3.4, I see the following message printed before any
task: “WARNING: user-level profile defined in project files.”

Also, the documentation explicitly clarifies the role of the `:user` profile:

> The `:user` profile is separate from `:dev`; the latter is intended to
> be specified in the project itself. In order to avoid collisions, the
> project should never define a `:user` profile, nor should a user-wide
> `:dev` profile be defined.

Top-level `:dependencies` aren’t bad.
-------------------------------------

In fact, they’re still used in Leiningen’s own project files.

- https://github.com/technomancy/leiningen/blob/2.3.4/project.clj#L9
- https://github.com/technomancy/leiningen/blob/2.3.4/sample.project.clj#L45
Commit to Leiningen 2. Remove `:dev-dependencies`.

Each of jars listed under the (“Lein1-style”) `:dev-dependencies` is
already present in the (“Lein2-style”) `:dev` profile’s `:dependencies`
vector.
Drop the patch-num from the version profile names.

It seemed distasteful to me to have a profile named `:1.5.0` and yet
have Clojure 1.5.*1* be under test. Just to be consistent,
I changed `:1.4.0` and `:1.3.0` too.
Remove redundant dependencies on `java.jdbc`.

Even if you specify to Leiningen that you _only_ want a certain profile
activated —e.g., `lein with-profile 1.3 …`— the top-level dependencies
are still merged in.
Extract common JDBC-connector dependencies.

Even if you run `lein with-profile 1.3 test`, the `:test` profile (and
its associated dependencies!) are merged into the project map, so we
don't need to worry about creating, e.g., a test profile for Clojure
1.3, a test profile for Clojure 1.4, a test profile for Clojure 1.5, etc.

Oh, and I'm just gambling that Postgres and Criterium really are meant
as dev-dependencies and not test-dependencies.
Merge branch 'clean-up-project.clj'