Fix cloverage version in lein-cloverage.
Allow overriding cloverage version from the env
Use RELEASE if no version is provided.
Merge pull request #5 from JacekLach/plugin-cloverage-version

Plugin refers to cloverage 1.0.0-SNAPSHOT instead of 1.0.1
Prepare release lein-cloverage 1.0.2
Bump lein-cloverage to 1.0.3-SNAPSHOT.
Update installation instructions.