SharedField: add operator== and operator!=

fixes #186
Interval: add interval parsing support

Class interval holds intervals (chr, start, stop) and can read and write
all the following interval types: BED, GATK and PICARD. Functionality
includes:

* Creating and manipulating Interval objects
* Reading interval files in any of the three formats (including mixed formats)
* interval tiling routines
* tests for the entire API

Doesn't include:

* header validation for picard format
* interval set operations (todo)

fixes #163
Merge pull request #200 from broadinstitute/mc_interval_support_163

Interval: add interval parsing support
Merge pull request #197 from broadinstitute/mc_operator_equals_shared_186

SharedField: add operator== and operator!=
IndividualField: add operator== and operator!=

Add implementation of the two operators for both IndividualField and
IndividualFieldValue so we can write tests more easily and compare
objects. Comparison is based on value equality. The Genotype class
already had the operators implemented (thanks @kshakir)

fixes #187
Merge pull request #198 from broadinstitute/mc_individual_operator_equals_187

IndividualField: add operator== and operator!=
Sam: remove custom move operations, make them default and move all API docs to the header file
Sam: remove debug printf message
SamBuilder: make move operations default
Gamgee: add interval.h
address pesky reviewer's comments