Add read/write support for zip64 extensions

This commit adds the capability of creating archives larger than
4GB via zip64 extensions. It also fixes bugs reading archives of
this size (specifically, the 64-bit offset of the local file
header was not being read from the central directory entry).

To maximize compatibility, zip64 extensions are used only when
required. Unfortunately, at the time we write a local file header,
we don't know the size of the file and thus whether a Zip64
Extended Information Extra Field will be required. Therefore
this commit writes a 'placeholder' extra field to reserve space
for the zip64 entry, which will be written if necessary when
we update the local entry with the final sizes and CRC. I use
the signature "\x99\x99" for this field, following the example
of DotNetZip which does the same.

This commit also adds a rake task, zip64_full_test, which
fully tests zip64 by actually creating and verifying a 4GB zip
file. Please note, however, that this test requires UnZip
version 6.00 or newer, which may not be supplied by your OS.
This test doesn't run along with the main unit tests because
it takes a few minutes to complete.
fix string encoding of zip64 header ids for ruby 2.0
Merge pull request #99 from jstanley0/master

Add read/write support for zip64 extensions
Add missing Zip::Entry arguments to Zip::File#get_output_stream. Fixes rubyzip/rubyzip#100
Fix #102 recover file permissions if zip file was exist
disable jRuby for a while
Merge pull request #101 from ProGNOMmers/issue_100

Add entry arguments to Zip::File#get_output_stream. Fixes rubyzip/rubyzip#100
Fix #28 and #103
fix jRuby Building #104
Fix #106 Set options about restoring ownerships, permissions and times. restore permissions enabled by default.
Update README to reflect 1.9 requirement
Update Changelog with Ruby 1.9 requirement
Merge pull request #107 from twelvelabs/master

Document change in Ruby version
Version bump
Make File.open_buffer support Tempfiles
Merge pull request #113 from jimryan/master

Make File.open_buffer support Tempfiles
Update README.md

add Method `get_output_stream` in basic code
Merge pull request #114 from groverz/patch-1

Update README.md
Update README.md
Fix Rubinius by adding newly required gems, updating label in .travis.yml