Added config and test file for Endless.

The configuration file encodes as much of our style
guide as JSCS is currently capable of.

The test file "lint_test_file_bad.js" tries to violate
all of our style rules at least once. To test the test
file, after installing JSCS via npm:

jscs ./test/endless_bad_file.js --config=./presets/endless.json

This should output the errors found by JSCS.

[endlessm/eos-sdk#2545]
Added JSHint integration.

The shell script lint.sh runs both linters on a given
file. Currently, both configuration files must be passed in.
The second argument should be the jscs config file, and the
third should be the jshint config file.

[endlessm/sdk#2545]