Add option to specify host address

build(deps): [security] bump node-notifier from 8.0.0 to 8.0.1 in /webui

'--host'-cmdline-option is added to the webui command.

Previously, the WebUI couldn't be hosted inside of a container. As the
WebUI-server only listend per default to localhost and there was no
option to change the address, the server should listend to. This means,
that the WebUI was only reachable from localhost. So only from inside of
the container but never from outside.
The '--host'-option allows to set the IP address or a hostname
which the WebUI-server should listen to. E.g. by setting 0.0.0.0 or ::
as address.

Update documentation for new option.

Update shell completion for new option.

Compilation seems to add another go-gitlab version.

build(deps): bump github.com/spf13/cobra from 1.1.1 to 1.1.3

build(deps): bump github.com/xanzy/go-gitlab from 0.40.1 to 0.44.0

Bumps [github.com/xanzy/go-gitlab](https://github.com/xanzy/go-gitlab) from 0.40.1 to 0.44.0.
- [Release notes](https://github.com/xanzy/go-gitlab/releases)
- [Changelog](https://github.com/xanzy/go-gitlab/blob/master/releases_test.go)
- [Commits](https://github.com/xanzy/go-gitlab/compare/v0.40.1...v0.44.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [github.com/spf13/cobra](https://github.com/spf13/cobra) from 1.1.1 to 1.1.3.
- [Release notes](https://github.com/spf13/cobra/releases)
- [Changelog](https://github.com/spf13/cobra/blob/master/CHANGELOG.md)
- [Commits](https://github.com/spf13/cobra/compare/v1.1.1...v1.1.3)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Add ability to search by arbitrary metadata

Example:

~/git/git-bug/git-bug ls --metadata github-url=https://github.com/author/myproject/issues/42

or

~/git/git-bug/git-bug ls metadata:github-url:\"https://github.com/author/myproject/issues/42\"

Fixes the cmdline part of <https://github.com/MichaelMure/git-bug/issues/567>.

Commits for issues #554, #564 and #566

- New build after removing images from public folder

- Remove images for ReactJS, MaterialUI, GraphQL and Apollo GraphQL

Having the resolver in Definition doesn't actually work well as the resolver
is very situational.