Custom style from shield.io and some refactoring

[uniibu]

Status:

• Travis-ci Build passed

Major Changes:

• Added support to shields.io's style parameters and this should also satisfy https://github.com/greenkeeperio/greenkeeper/issues/416. With this PR, greenkeeper can now accept a style paramater and supports flat flat-square and plastic style from shields.io.
• Change the word enabled to monitored

Minor Changes:

• Refactored and rearranged some codes
• Changed 'Greenkeeper' word on the badge to the standard badge lettering which is all lower-case.
• Added example badges on README
• Change left-side badge color to make the badge unique
• Added tests for the new style query
• Update Hapi.js version on the package.json
• Added package-lock.json on gitignore.
• Since the engine recommends the Node version to be 7, i would assume, its the latest of the v 7 releases, and version lower than 7.10.1 are labeled to be high severity vulnerability july-2017-security-releases, i've set the recommended version to ^7.10.1 || >= 8.1.4
• And because of the node version change, --harmony flag is no longer needed, so i removed it.

Badges will look like the following:(flat-square,flat, plastic)

PS. Feel free to edit ☺️

[levithomason]

It would be great to get statuses similar to what gemnasium supports like "up to date" and "out of date".

May also consider sticking with the usual dark gray background on the left:

https://github.com/Semantic-Org/Semantic-UI-React

Others looking may consider using something like https://david-dm.org instead.

[j-f1]

Why not use the Greenkeeper green for the enabled/monitored background color? It’s already green, so it’d be less of a change. You could also change the left side to say “🌴 greenkeeper” to stay closer to the brand.

[kbrandwijk]

I am a big fan of the 'for-the-badge' style. Any reason why that's not included?

[uniibu]

This pull request was from an older version of greenkeeperio/badges (Aug. 2017). Im closing this this pull request and creating a new one to keep things clean. I've also noted your comments @janl and will update accordingly. Cheers