Merge pull request #31 from homonecloco/master

Release of samtools 2
Regenerate gemspec for version 2.0.3
Added the depency  'open3' as a global require. (It is required in some environments)
Regenerate gemspec for version 2.0.3
Fixed conflict
Regenerate gemspec for version 2.0.4
Added reheader bam file
Regenerate gemspec for version 2.0.4
Merge branch 'master' of github.com:helios/bioruby-samtools
Removed old or unneeded files
Added code to plot_coverage for option merging
Updated tutorial
Merge pull request #33 from ethering/master

Updated code to make plotting coverage more flexible
Merging with ethering bugfixes