v2.0.0 release

travis: install rpm

See CHANGELOG.md

Fix change log tag format

[1.2.0] - 2017-12-27

--------------------

- No significant code changes from rc2

Merge branch 'release/1.2.0'

[1.2.0-rc2] - 2017-12-15

------------------------

- `rest/client` types `MessageHeader` and `Message` with convenience methods;
  provides a more natural API
- Powerful command line REST
  [client](https://github.com/jhillyerd/inbucket/wiki/cmd-client)
- Allow use of `latest` as a message ID in REST calls

- `rest/client.NewV1` renamed to `New`
- `rest/client` package now embeds the shared `rest/model` structs into its own
  types
- Fixed panic when `monitor.history` set to 0

Release 1.2.0-rc1

Added
- Storage of `To:` header in messages (likely breaks existing datastores)
- Attachment list to [GET message
  JSON](https://github.com/jhillyerd/inbucket/wiki/REST-GET-message)
- [Go client for REST
  API](https://godoc.org/github.com/jhillyerd/inbucket/rest/client)
- Monitor feature: lists messages as they arrive, regardless of their
  destination mailbox
- Make `@inbucket` mailbox prompt configurable
- Warnings and errors from MIME parser are displayed with message

Fixed
- No longer run out of file handles when dealing with a large number of
  recipients for a single message.
- Empty intermediate directories are now removed when a mailbox is deleted,
  leaving less junk on your filesystem.

Changed
- Build now requires Go 1.7 or later
- Removed legacy `integral` theme, as most new features only in `bootstrap`
- Removed old RESTful APIs, must use `/api/v1` base URI now
- Allow increased local-part length of 128 chars for Mailgun
- RedHat and Ubuntu now use systemd instead of legacy init systems

Added

=====
- Homebrew inbucket.conf and formula (see README)

Fixed
=====
- Log and continue when unable to delete oldest message during cap enforcement

- Message Cap to status page

- Search-while-you-type message list filter

- Shutdown hang in retention scanner
- Display empty subject as `(No Subject)`