v2.0.1

• Breaking change Port stellar-sdk to Typescript. There should be no changes
  in functionality (Besides TS type definitions). But because the build process
  has changed, there could be some unanticipated bugs. Here's a description of
  the type definitions that changed:
  • Types that were once in the Server namespace but didn't actually deal with
    the Server class have been broken out into a new namespace, ServerApi.
    So, for example, Server.AccountRecord -> ServerApi.AccountRecord.
  • Server.AccountResponse is out of the Server namespace ->
    AccountResponse
  • Server.*CallBuilder is out of the Server namespace -> *CallBuilder
  • HorizonResponseAccount is now Horizon.AccountResponse
• Upgrade Webpack to v4.
• Add support for providing app name and version to request headers.
• (NPM wouldn't accept the 2.0.0 version, so we're publishing to 2.0.1.)

Many thanks to @Ffloriel and @Akuukis for their help with this release!