Supply temporary directory to java_test()

Similar to genrule() give the test running JVM a temporary directory
below buck-out that is uniquely named for this test target. Send
the path in by both the TMP environment variable and java.io.tmpdir
system property.

Fixes https://github.com/facebook/buck/issues/13
Supply temporary directory to genrule() invoked java_binary()

JVMs on UNIX systems typically hardcode to use /tmp as the default
temporary area, unless system property java.io.tmpdir is set on
the command line. Pass the genrule's TMP location to the binary
as a system property so it can be used automatically.