Exclude Trending reports from Dashboard widgets.

Changed code to exclude Trending reports from widget editor because those are not like regular reports and do not have columns. Show a message instead of third pull-down "No Reports to select" in the view.

https://bugzilla.redhat.com/show_bug.cgi?id=1163952
Refactored code in schedule_menus method.

- Renamed schedule_menus method to report_selection_menus, and changed all it's callers.
- Moved report_selection_menus method to reports controller, as it is a common method schedules and widgets editor.
- Added spec tests for report_selection_menus method
- Changed message to be displayed for folders that do not have reports .

https://bugzilla.redhat.com/show_bug.cgi?id=1163952
Converted view to haml.

- Used gettext to display "No Widget compatible Reports found" message.

https://bugzilla.redhat.com/show_bug.cgi?id=1163952
Rewritten miq_template view to HAML + added gettext calls

Obsolete views were removed
Fixed misspelled "capitalize" and added flash message to view

Fixed misspelled "capitalize" when creating error message for adding duplicate Compute Chargeback Rate
Added flash message definition to Chargeback Edit view

https://bugzilla.redhat.com/show_bug.cgi?id=1073366
Sprint 16 Changelog updates

Updated links.
Added known bullet points.
Added bullets from sprint report.
Removed extra line and character spaces.
Made sentence case corrections.
Added notable fixes

[skip ci]
Merge pull request #1142 from mfeifer/changelog

Sprint 16 Changelog updates
Merge pull request #1106 from skateman/gettext-haml-miq_template

Rewritten miq_template view to HAML + added gettext calls
Merge pull request #1159 from GregP/chargeback_rate_capitalize_msg

Fixed misspelled method name (capitalize)
Merge pull request #1115 from h-kataria/exclude_trending_reports_in_dashboard_widget_editor

Exclude trending reports in dashboard widget editor
Config/Application.rb: Use path as String for config.autoload_paths

We pushed instances of class Pathname instead of paths as String to
config.autoload_paths. That caused fails in 'rake gettext' tasks.
Gemfile: Added 2 rubygems to enable rake gettext task

Added to Gemfile's development group:
- gettext
- ruby_parse