Fixes #826; Redirect info messages to *err*

I decided to leave some messages alone. Specifically

 * messages which look like stacktraces
 * messages which instruct the user to take some sort of action

Arguably the stacktraces should go to stderr but I thought I'd leave
those open for discussion. Any others that remain represent errors on
my part.
Use warn instead of info where applicable
Pick up a 'WARNING' that got missed
Don't try to read non-forms in sjacket->clj.
Document change task; stop using prime marks in local names.
Update `collapse-fn` tests to illustrate argument order

Didn't like having a property that was so crucial ingored in the tests
Skip anaemic helper
Whitespace and test group merge
Implement artifact/group-id editability
Fixup regular expression to be less lenient
Reappropriate `bump-version` function for `lein.change` usability

One wart to notice is that argument order is switched between
`bump-version-map` and `bump-version`. This is because the `lein.change`
semantics enforce that version-string is the first argument.

Have not added tests for this function, do you think we should?
Update `leiningen.change` tests to use real `bump-version`

Not sure what you think of creating this kind of coupling in the tests.

This were useful tests for driving the previous commits, but happy to
delete them now.
Fix things broken by late rename

Note to self:

Always unload namespaces and test again after renaming.
Merge remote-tracking branch 'waynr/lein-release'

# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
#
# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.
Make bump-version work with strings and default to bound *level*.
Merge remote-tracking branch 'crisptrutski/lein-release-and-change-interop'

Conflicts:
	src/leiningen/release.clj
	test/leiningen/test/release.clj
Merge remote-tracking branch 'crisptrutski/set-group-or-artifact-id'

Conflicts:
	src/leiningen/change.clj
Merge remote-tracking branch 'cddr/826-info-messages-to-stder'

Conflicts:
	leiningen-core/src/leiningen/core/classpath.clj
Silence warn calls when LEIN_SILENT is set.
Document the release task.

Also adds sample alternate release workflow in sample.project.clj.