Restore use of FileOutputStream in ChannelDescriptor.

We use FileOutputStream here because it can handle append mode
for us, as opposed to RandomAccessFile which requires us to do
our own seeking. I am restoring this with documentation and Jose
will provide a new patch that only flips to RAF when we need to
provide an offset.
Update to HEAD of jruby-launcher
When offset passed return RandomAccessFile when not return FileOutputStream
Clear nexter on rewind, to avoid it accidentally being used.
Merge pull request #724 from josedonizetti/hasoffet_flag

When offset passed return RandomAccessFile when not return FileOutputStream
Update to use official 1.0.10 version of jcodings
Make joni use newly released joni 2.0.0 (now with interrupts)
Merge remote-tracking branch 'github/master'
Revert "REFACTORING: supporting flag about receiving an offset or not."

This reverts commit 05de78e644b1db4a3b7af74f014cf27fd54cea0d.
IO.binwrite doesn't truncate the file if an offset is given
Switch to using ModeFlags in order to specify CREAT and RDWR at the same time
Fix string concatenation with a number as per rubyspec behaviour.

Following https://github.com/tychobrailleur/jcodings/commit/8536b4fdeecf3dec31ca868803654b3ab7829915, the incorrect behaviour of String#concat with
a number was made obvious by throwing an EncodingException.  MRI changes
the encoding of the String if the concatenated codepoint is within
ASCII-8BIT range, and throws a RangeError otherwise.
ACK merge when I wanted to rebase
Make regexp interruptible.  Regexp will throw InterruptedRegexpError < RegexpError
Merge pull request #726 from jruby/io_binwrite_dont_truncate_with_offset

IO.binwrite doesn't truncate the file if an offset is given
Tag failing Socket::BasicSocket#ioctl rubyspec
Remove 1.9 specs from travis allow_failures
IO.binwrite should accept options hash
Refactored directed graph specs
20: Don't include kwargsRest as final arguments to rest arg