v2.2.0 - Feature Release: TypeScript

[DEPRECATED] Please update to v2.2.1, release contains a broken CLI bin/rlp
command!

First TypeScript based release of EthereumJS libraries, thanks @krzkaczor,
@GrandSchtroumpf, @whymarrh, @holgerd77 for the great work on this!

This release doesn't introduce any main new features but will serve as a basis
for further TypeScript transitions coming along with greater type safety
for EthereumJS libraries. If you are developing in TypeScript you can
further already benefit from the RLP type declarations published from now on
along new releases.

See PR #37 and subsequent PRs merged
towards the associated typescript branch to get an overview on the changes.
The release also comes along with the introduction of a new repo
ethereumjs-config centralizing
configuration for EthereumJS libraries on TypeScript itself as well as
linting, formatting and testing.

This release passes all existing unit tests and other checks. If you nevertheless
experience problems please report on the EthereumJS
Gitter channel.

Other changes:

• Added LICENSE file for MPL2.0, see PR #31