memoize call to gpg credentials
Document :certificates.
Replace :env values in :repositories with lookups from environment.

Needed for unattended builds.
NEWS for preview6.
Add bin/release.
Register certificates before calling get-classpath.  Fixes #613

We need to do this as get-classpath can itself trigger the downloading
of dependencies.  This also ensures leiningen-core/resources is added to
the classpath by the wrapper scripts.
Merge pull request #621 from ato/early-register-certs

Register certificates before calling get-classpath.  Fixes #613
Load SSL certificates even when running outside of a project. Fixes #613

We now treat them much the same as plugins, loading them explicitly
from the user and default profiles when the project is nil.
When outside project load the default project map. Fixes #613

The default certificates and repositories are in project/defaults
so we need to include it explicitly.  The reason load-plugins knew
to try clojars at all is that normalize-repos explicitly adds the
default repos.  This obviously doesn't happen for other keys such as
:certificates though.
Merge pull request #622 from jaceklaskowski/master

Read user profiles once (it uses IO so it should be faster)
Release 2.0.0-preview6
Minor fix to avoid this error:

./lein: line 180: [darwin11: command not found
Merge pull request #626 from Knekkebjoern/master

'command not found' in bin/lein
Improve defproject docstring.
Don't mess with HTTP_CLIENT setting. Fixes #623.
Use env in bash shebang. Fixes #624.
Remove outdated comment about ant.

[ci skip]
Bump Bultitude version. Fixes #592.
Document using .lein-classpath for developing plugins. Fixes #508.

[ci skip]
Remove left-over use of integer error code in classloader eval.