Switch to version 0.2.0 of the API specification

Change

• Update for version 0.2.0 of the Budget Data API
• Change accountsPost to accountPost

Fix simple bug

Fixed

• Fix typo in constructor

Add `BudgetDataApiClient` wrapper class

Added

• Add wrapper class for easier use

Cleanup and getting current

Fixed

• Remove unneeded files
• Update supported PHP versions
• Update dependencies
• Leave version numbers to git tags and Packagist, not hard-coded in composer.json

Add, list accounts

Added

• Add ability to add an Account
• Add ability to list Accounts