Respect JAVA_HOME over the PATH configuration (if JAVA_HOME is set).
Fixed group-id for sbt-0.11.3.

Also fixed curl's args so it will fail and not write a file on errors.
Default version 0.11.3, snapshot 0.13.0-SNAPSHOT.
option to configure path for storing sbt launcher jars
Tweaked the launch dir setting a little.

It's called -sbt-launch-dir now.
Adding simple installation instructions.
Fixed typo in help
Added the "universal" sbt launcher.

And cleaned up the echoes, more going to stderr so as not to
compromise output collection.
Bumped release default to 0.12.0-RC3.  Close enough.

And oh yeah, 2.9.2 came out.
sbt 0.12 release.
Apparently it's 0.12.0.

And checked in the 0.12.0 jar.
update sbt version
Updated bundled launcher to 0.12.1 as well.
Merge commit 'refs/pull/28/head'
Merge commit 'refs/pull/27/head'
Merge commit 'refs/pull/19/head'
respect `sbt_dir` from command line
not override `sbt.global.base` if `-no-share` was given
Merge commit 'refs/pull/31/head'
Updated various bits for sbt 0.12, plus -trace and -prompt.

 -trace: set the stack trace level
-prompt: set the sbt prompt