match repository if remote name equals Gerrit project name

Resolves #83
add troubleshooting hint for case when change list is empty

- now a remote whose name equals the Gerrit project name with Gerrit as remote url can be added

Related to issue #83
update README.md and iml-file

- add some more details about building and developing the plugin
- correctly mark test resources directory for rest api client
refactor changes browser

- extract code related to RepositoryChangesBrowser from
  GerritToolWindow to separate provider class
- this refactoring should make it easier to implement some
  of the features requested in #19, #20, #22, #80
Merge pull request #84 from forrert/update-readme

update README.md and iml-file
Merge pull request #85 from forrert/refactor-changes-view

Refactor changes view
show comments and drafts count in changes browser

- for each file in the changes browser
- made ReviewCommentSink observable (to be notified of new or
  deleted/removed comments)

Closes: #80
add PathUtils class

- move getRelativePath to new utils class (multiple usages)
Merge pull request #86 from forrert/changes-browser/file-comment-count

show comments and drafts count in changes browser
implement possibility to select diff base in change viewer

- previous revisions or the change's base can be selected as
  a diff base
- comments in RevisionCommentSink are now linked to a
  revision as well as the change
- related to issue #22
Merge pull request #88 from forrert/changes-browser/diff-base

implement possibility to select diff base in change viewer
add commit message as a file to the changes browser

- similar to gerrit's web UI the commit message is now displayed as
  a file in the changes browser view
- comments can be viewed and added just like with other files
- resolves #87
better support for merge commits CommitMessageFormatter

- support commits with more than 2 parents
Merge pull request #89 from forrert/changes-browser/commit-message

add commit message as a file to the changes browser
improve notification and error handling for review & submit action

- show message in status bar when these actions are successfully executed
- some refactoring for more intuitive exception handling in GerritUtil
  (make sure consumers/callbacks are only executed, when REST call
  was successful or no error message was provided)
- resolves #90
Merge pull request #95 from forrert/features/actions-notifications

improve notification and error handling for review & submit action
add support to select patch sets

- add new editable column to select the patch set to be displayed
  for each change in the changes list
- all actions on the changes list row are now based on the selected
  patch set (review, cherry pick, etc)
- display changes for the selected patch set in the changes browser
- display and add comments for the selected patch set in diff view
- resolves #22
improve column to select patch set in changes list

- change title to "Patch Set"
- add total number of patch sets to each entry
improve column to select patch set in changes list

- show a little down arrow in the column to better hint that a value
  can be selected in this column
fix concurrency issue when selecting a change from the list

When selecting two changes from the changes list shortly after each
other, the changes browser on the right may display the wrong change
because fetching the git commit may take longer for the first selected
change. The changes from the second selected change are then wrongly
overwritten by the first change. This commit fixes the wrong behaviour.