chore: add grunt support and fix some jshint issues
style: fix jshint 'assignment vs expression' issue

Fix for "Expected an assignment or function call and instead saw an expression."
style: add missing semicolons in examples
style: use 'singlequotes' in examples
style: fix 'variable' used out of scope in examples
chore: add 'window' inline global comment
chore: add grunt-complexity as dependency

Add new grunt task `$ grunt complexity`.
The standard setup is tweaked to make the task pass.

Current offending file is:

 * lib/runner/reporters/junit.js (maintainability 98.653)
 * lib/index.js:60 - <anonymous>.setOptions is too complicated
      Cyclomatic: 11
      Halstead: 26.585106382978722
        | Effort: 45620
        | Volume: 1716.0
        | Vocabulary: 64
 * lib/index.js:197 - <anonymous>.printResult is too complicated
      Cyclomatic: 11
      Halstead: 30.183673469387756
        | Effort: 60571
        | Volume: 2006.7
        | Vocabulary: 66
chore: integrate grunt into travis build
Merge branch 'basic-grunt-support' of https://github.com/davidlinse/nightwatch into davidlinse-basic-grunt-support

* 'basic-grunt-support' of https://github.com/davidlinse/nightwatch:
  chore: integrate grunt into travis build
  chore: add grunt-complexity as dependency
  chore: add 'window' inline global comment
  style: fix 'variable' used out of scope in examples
  style: use 'singlequotes' in examples
  style: add missing semicolons in examples
  style: fix jshint 'assignment vs expression' issue
  chore: add grunt support and fix some jshint issues
chore: remove options for unused uglify-task
chore: split complexity-task into separate tasks

Allow more control about the complexity for `lib/`
and `example` code and add two new grunt tasks.
```
$ grunt complexity:lib
$ grunt complexity:examples 
```
chore: add 'unsued:true' to .jshintrc
style: remove unused require'd modules
Merge branch 'basic-grunt-support' of https://github.com/davidlinse/nightwatch into davidlinse-basic-grunt-support

* 'basic-grunt-support' of https://github.com/davidlinse/nightwatch:
  style: remove unused require'd modules
  chore: add 'unsued:true' to .jshintrc
  chore: split complexity-task into separate tasks
  chore: remove options for unused uglify-task
disabled unused jshint warnings and renamed the default grunt task
merged from master
Merge branch 'davidlinse-basic-grunt-support'

* davidlinse-basic-grunt-support:
  disabled unused jshint warnings and renamed the default grunt task
  style: remove unused require'd modules
  chore: add 'unsued:true' to .jshintrc
  chore: split complexity-task into separate tasks
  chore: remove options for unused uglify-task
  chore: integrate grunt into travis build
  chore: add grunt-complexity as dependency
  chore: add 'window' inline global comment
  style: fix 'variable' used out of scope in examples
  style: use 'singlequotes' in examples
  style: add missing semicolons in examples
  style: fix jshint 'assignment vs expression' issue
  chore: add grunt support and fix some jshint issues