Added Gitter badge
Remove various implicit globals in Angular app

This patch does not remove globals used by timelines model: removing
these accidental globals would require addressing a number of
circular dependencies, e.g. between `Timeline` and `Project` objects.

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Fix Karma tests reliant on implicit globals

See a3a07f43.

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Fix missing PathHelper dependency in WPController

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Test WP's spent hours property with read permission
Respect time entry view permission

Conflicts:

	app/models/work_package.rb
Fix cuke
Test that version custom field is correctly displayed
Display custom fields of type version
Merge pull request #2182 from opf/hotfix/17283_value_for_version_custom_field_not_displayed_in_split_view

17283 value for version custom field not displayed in split view
Merge pull request #2190 from opf/hotfix/4_17304_view_time_entries_permission_not_respected_on_wp_spent_hours

17304 view time entries permission not respected on wp spent hours
Rebuild JS package if JS translations change
Merge pull request #2152 from gitter-badger/gitter-badge

Add a Gitter chat badge to README.md
slightly change the position of the gitter badge
Merge branch 'release/4.0' into feature/merge_release_4_into_dev

Conflicts:
	app/assets/javascripts/angular/work_packages/controllers/details-tab-overview-controller.js
	app/models/work_package.rb
	config/locales/js-de.yml
	config/locales/js-en.yml
	karma/tests/work_packages/controllers/details-tab-overview-controller-test.js
Test that for an empty value a default text is rendered
Render a placeholder if description is empty
Merge pull request #2198 from opf/feature/merge_release_4_into_dev
Merge pull request #2183 from opf/hotfix/remove-js-globals
Merge branch 'release/4.0' into feature/merge_release_4_into_dev

Conflicts:
	app/assets/javascripts/angular/helpers/path-helper.js
	app/assets/javascripts/angular/models/filter.js
	app/assets/javascripts/angular/services/timezone-service.js
	app/assets/javascripts/angular/timelines/directives/timeline-container-directive.js
	app/assets/javascripts/angular/ui_components/focus-helper.js
	app/assets/javascripts/angular/work_packages/controllers/work-packages-controller.js