[Truffle] Add a method to dump the stack trace.
[Truffle] Add method name to backtrace output, MRI-style.
[Truffle] Show the values of local variables in the stack trace!

* RubyCallStack.dump() now takes a RubyContext.
* RubyNode.panic2() is removed as unused.
* Use java.io.tmpdir for default Etc.systmpdir.  Enables changing Dir::tmpdir using a Java system property.
Merge pull request #1832 from eregon/truffle_backtrace

Show method names and local variables in Truffle backtrace
* Update the path to the requireTest jar
Fix another test broken by move.
Add JDK and Maven prereq's to BUILDING.
Disable this test temporarily (#1833)
Merge remote-tracking branch 'github/master'
Merge branch 'master' into dynbuf_io