Add LICENSE file to project templates

Projects created by "lein new" are meant to be licensed under the EPL as noted
in project.clj and README.md. One requirement of the EPL is, however, that "a
copy of this Agreement [the EPL] must be included with each copy of the
Program." [0].

This means that projects created by leiningen cannot be legally distributed if
the author fails to add the LICENSE him/herself. This patch fixes this issue
by creating a LICENSE file with a plain text copy of the EPL 1.0 (cf. [0]) by
default for new projects.

[0] http://www.eclipse.org/legal/epl-v10.html → 3. REQUIREMENTS