* add yamllint command to travis CI

installs and runs a linter across the YAML in the
project to ensure consistency in the written YAML.

this uses yamllint and the default yamllint config with
"truthy" and "line-length" disabled.

* run dos2unix on CRLF files

* YAMLLINT: remove trailing spaces

* YAMLLint: add YAML document start

* YAMLLint: too many spaces around bracket

* YAMLLint: fix indentation

* YAMLLint: remove duplicate key

* YAMLLint: newline at end of file

* YAMLLint: Too few spaces after comma

* YAMLLint: too many spaces after colon

The root command will run node checks and if possible master checks.
I've also added some Makefile targets to improve local testing and improve the documentation.