Add project to filter query

Closes #45
add info about installing download-commands plugin to README.md
Merge pull request #68 from forrert/update-readme

add info about installing download-commands plugin to README.md
Merge pull request #67 from forrert/fixes/project-in-query

Add project to filter query

Closes #45
fix typo
separates GerritRestClient into GerritApiImpl and GerritRestClient

- GerritApiImpl implements GerritApi interface and gives access to
  endpoints provided by gerrit rest interface
- Renamed GerritRestClientFactory to GerritApiFactory and made its
  #create methods return GerritApi instead of an implementation thereof
- GerritRestClient does not implement GerritApi (anymore) but provides
  basic http access to the gerrit rest interface

 Related to issue #56
add test class for ChangesRestClient

- added tests for generating url in #query methods

Related to issue #56
improve usability for file comments

- display actions in popup-menu
- add actions to edit and remove own comment
- add action to reply (also with short-cut-action "Done")
- add keyboard shortcut "c" to add a new comment
- major refactoring

Resolves #18
fix bug in Gson date deserializer

- hours are in 24 hour format (not 12)
- spotted and fixed by Thomas Forrer
adopt to recent changes in Gerrit extensions-api

Related to issue #56
refactor ChangesRestClient

- extract json-parsing part into ChangesParser
- add unit test for ChangesParser
- fix bug in DateDeserializer (wrong pattern for date parsing)

Related to issue #56
refactor ProjectsRestClient

- extract json-parsing part into ProjectsParser
- add unit test for ProjectsRestClient and ProjectsParser

Related to issue #56
implement ChangeApiRestClient#addReviewer

Related to issue #56
Merge remote-tracking branch 'remotes/uwolfer/master'

Conflicts:
	src/main/java/com/urswolfer/gerrit/client/rest/http/changes/ChangeApiRestClient.java
	src/test/java/com/urswolfer/gerrit/client/rest/http/GerritRestClientTest.java
refactor AccountsRestClient

- split parsing part to AccountsParser
- add unit tests for parser and rest client

Related to issue #56
Merge pull request #69 from forrert/refactor-rest-client

Suggested changes to refactoring Gerrit rest api
Merge pull request #72 from forrert/accounts-endpoint

Accounts rest endpoint
improve file comment balloon hint

Related to issue #71
refactor AccountApiRestClient

- pass GerritRestClient to AccountsApiRestClient
  instead of AccountsRestClient

Related to issue #56
Merge pull request #73 from forrert/accounts-endpoint

refactor AccountApiRestClient