Major and minor changes as well as fixes release

Major changes

• Rich Text editor for ticket body text
• New filter hook: ns_wp_editor_specs, ns_back_to_knowledgebase
• Pending ticket notification using admin menu bubble
• Fixed translation strings to strip out dumped HTML and made most of them SQL injection proof
• Composer, npm dependency and Grunt incorporated for easy development collaboration
• Default assignment of 'Support' department is made deprecated
• User can choose Support Department on submitting new ticket (Settings available)
• CSS is changed from LESS to Sass
• System Status admin page

Minor changes

• Reorganized third party libraries
• contributing.md added
• Github issue template added
• A warning on upgrading process fixed - props @prionkor
• jshint error fixed with procedural code
• Agent email was not sending - fixed
• Ticket response content added to email body
• Back link to Knowledgebase added after Knowledgebase contents