Merge pull request #1 from chmille4/master

added fragment length stats
Factored out the BAMTOOLS variable into the shell
now instead of defining BAMTOOLS in Makefile, it is taken from the shell
To build, use the form of `BAMTOOLS=<path-to-bamtools> make'
Merge branch 'master' of https://github.com/chmille4/bamstatsAlive
Using the library 'jansson-2.5' to handle json
BUGFIX: Alignment Histogram data was improperly constructed
Merge branch 'master' of https://github.com/yiq/bamstatsAlive into test_pull