docs: update readme file
docs: update readme usage section
docs(readme): style updates
refactor: update pkg json file

Optimization for npm.
chore(npm): add .npmignore file
chore(pkg.json): add .git suffix to git repo url
docs: add npm to intall section
fix: value rounding issue in some cases

Was present with e.g. `<input type="range" min="0.1" max="3" step="0.1"
value="0.5" data-rangeslider>`
The value `1.7` returned `1.7000000000000002` and
`1.9` was `1.8999999999999997`.

* add dynamic toFixed digit based on step length to format the value

closes #103
example: add more floating point cases
fix: update grunt banner to use `pkg.license.type`

Fixes `/*! rangeslider.js - v0.3.6 | (c) 2014 @andreruffert | [object
Object] license…`
chore(release): v0.3.7
Merge pull request #105 from andreruffert/release-0.3.7

Release 0.3.7