Integrated igzip library to enable fast level 1 compression of BAM files.

New pull request to resolve issues with Travis CI

igzip enables faster level 1 compression on BAM files compared to zlib while providing similar compression ratio as zlib. (https://software.intel.com/en-us/articles/igzip-a-high-performance-deflate-compressor-with-optimizations-for-genomic-data).
Response to jmarshall:

1) Compiler reverted to gcc by including the stdc++ library.
2) Before this compression library was customized to Genomics it has been used in storage acceleration https://01.org/storage-acceleration-library, we don't expect the API to change.
3) Happy to create another branch, but would be great if the latest commit is first tested and reviewed.