common: add three checks to cstyle
examples: add Intel license to four source files
Merge pull request #15 from ldorau/examples-add-Intel-license

examples: add Intel license to four files
common: fix cstyle checking

Make cstyle check benchmark directory and correct cstyle errors
in this directory.
Merge pull request #16 from ldorau/common-fix-cstyle-checking

common: fix cstyle checking
Merge pull request #17 from ldorau/common-add-three-checks-to-cstyle

common: add three checks to cstyle
doc: add instructions for contributing

Fixes: pmem/issues#2