Separate global plugins/settings folder per sbt version

.sbt

## Note: the system property `sbt.global.base` was introduced in 0.10.1
## sbt-0.10.0 still uses the default global directory in ~/.sbt

gseitz@QBallz ~/.sbt % find . -name '*target*' -prune -o -print
.
./0.10.1
./0.10.1/plugins
./0.10.1/plugins/build.sbt
./0.10.1/plugins/project

sbt-0.10.0

gseitz@QBallz ~/dev/projects/sbt-protobuf (0.0.6) % /usr/local/Cellar/sbt/0.10.0/bin/sbt;   # LOOK MA, no global plugins loaded
[info] Set current project to default (in build file:/Users/gseitz/dev/projects/sbt-protobuf/)
> 

sbt-0.10.1

gseitz@QBallz ~ % cat `which sbt`
#!/bin/sh
test -f ~/.sbtconfig && . ~/.sbtconfig
exec java -Xmx512M ${SBT_OPTS} -Dsbt.global.base="$HOME/.sbt/0.10.1" -jar /usr/local/Cellar/sbt/0.10.1/libexec/sbt-launch.jar "$@"


gseitz@QBallz ~/dev/projects/sbt-protobuf (0.0.6) % sbt;                     # vvvvvv
[info] Set current project to default-270814 (in build file:/Users/gseitz/.sbt/0.10.1/plugins/)
[info] Set current project to default-47fcc8 (in build file:/Users/gseitz/dev/projects/sbt-protobuf/)
>