Finish updates to use JIRA gem

CHANGELOG.md

Gemfile

Gemfile.lock

app/models/project_services/bugzilla_service.rb

app/models/project_services/custom_issue_tracker_service.rb

app/models/project_services/gitlab_issue_tracker_service.rb

app/models/project_services/issue_tracker_service.rb

app/models/project_services/jira_service.rb

app/models/project_services/redmine_service.rb

config/gitlab.yml.example

db/migrate/20160122231710_migrate_jira_to_gem.rb

...20161011222551_remove_inactive_jira_service_properties.rb

db/migrate/20161025231710_migrate_jira_to_gem.rb

db/schema.rb

doc/integration/README.md

doc/integration/img/jira_add_user_to_group.png

doc/integration/img/jira_create_new_group.png

doc/integration/img/jira_create_new_group_name.png

doc/integration/img/jira_create_new_user.png

doc/integration/img/jira_group_access.png