Update extconf.rb to avoid deprecated/removed Gem.searcher method
Fix to ieee.c for Ruby 2.0 compilation
Merge pull request #9 from JamesHarrison/master

Fixes for Ruby 2.0
Ruby 2.1 support.

Added the patch from https://raw.github.com/jjk-jacky/abs/master/rb-gsl-jjk/fix-ruby-2.1.patch
Merge https://github.com/justinweiss/rb-gsl

Conflicts:
	ext/extconf.rb
	ext/ieee.c