Make remarks characters limit to 500
Make abbreviation not mandatory
Return error message JSON when entity is invalid

Conflicts:
	app/controllers/api/v1/organizations_controller.rb
Merge pull request #33 from Mura-Mi/modify-organization-validation

Modify organization validation
Fix remove button style
Add attachments feature
Add comments to Attachment
Fix degrade
Add attachments to Activity
Remove comments
Refactor application bootstrap
Set default sort
Add loading spinner
Fix degrade
Add Career
Assemble details view
Add statuses
Fix people grid view
Add Users