Fixed test

• Unit test is fixed.

Fixed subscribersApi

Related support issue: http://developers.mailerlite.com/v2/discuss/5778f919f1a7c10e00e4e39d

Fixed query parameters

Bug affected some non general GET methods.

PHP version requirement

PHP version requirement is fixed in composer.json.

Fixed some filenames

0.1.2

Campaigns API

Campaigns API added:

• create campaign
• add content
• trigger action (send or cancel)

Initial release

Currently available APIs:

• Groups API
• Subscribers API
• Fields API