add comments to jshint rules

This PR adds sensible comments to the `.jshintrc` file, retains every rule that previously existed and adds the following new rules:

```
  // Force all variable names to use either camelCase style
  // or UPPER_CASE with underscores.
  "camelcase": true,
  // Prohibit trailing whitespace.
  "trailing": true,
```

Additionally adds the following two opinionated rules, but under a clear banner to easily be configured. Opinions definitely diverge here but the rules have to be there for developers to change.

```
  // Enforce tab width of 2 spaces.
  "indent": 2,
  // Enforce use of single quotation marks for strings.
  "quotmark": "single",
```

Finally, two more rules were added related to not warn for the lack of `"use strict"`. I understand if you do not wish this be included.

```
  // do not complain for lack of 'use strict';
  "globalstrict": false,
  "strict": false,
```