Fixing issue from 1.1.17 changes

Fixing issues on the formatting of nested objects on 'application/json' requests
Fixing issue with extra data being sent in header.
Fixing issue to allow the creation of custom fields to be sent as form encoded.

UTF-8 Fixes

Fixes for UTF-8

Composer autoload with classmap

Merge pull request #62 from nvllsvm/master

Composer autoload with classmap

Fix support for broadcast entries

Merge pull request #59 from aweber/version-bump

Bump Version to v1.1.15

Composer support

Merge pull request #44 from aweber/add-composer-packagist

Add composer packagist

Fix utf8 encoding bug

We were double encoding the params before sending the request.