v1.0.0-beta.2

This is the second beta release of the IOTA Go library. All changes are breaking.

Changes:

• Adds the account package which encapsulates address management, persistence, promotion/reattachment into a single object.
• Adds a quorum based provider which allows to construct an API object which uses the responses of multiple nodes to construct a response.
• Requires all address parameters to the API object to include the checksum (must be 90 trytes long)