Ruby mogilefs-client 3.11.0

Ruby mogilefs-client 3.11.0

This release provides compatibility with net-http-persistent 3.x
while retaining support for the (API-incompatible) 2.x series.

Users of mainline Ruby 2.2+ get a workaround for excessive
garbage for uploading files.  This excessive garbage on IO#write
should be fixed when Ruby 2.5 gets released on Dec 25, 2017:
https://bugs.ruby-lang.org/issues/13085

There's also a few minor garbage reductions of small strings,
relying on the maintained cmogstored for Content-Range PUT
testing, and some minor build system and documentation updates.

12 changes since 3.10.0 (Aug 2016):

      avoid pointless capture in regexp
      use opt_str_freeze to avoid allocations in a few places
      new_file/common: simplify empty class declarations
      support net-http-persistent 3.x
      test: switch to cmogstored for testing Content-Range PUTs
      avoid excessive garbage on uploads with Ruby 2.2+
      socket_common: limit IO#write garbage workaround to <= 2.4
      freeze string literals in a few more places
      update URLS to HTTPS
      README: explain removal of NFS support
      doc: remove private email address linkage
      gemspec: remove olddoc development dependency