Merge pull request doccano#918 from doccano/fix/doccano#481

Fix ApproveLabelsAPI not to show other's annotations if it's checked

Merge pull request doccano#670 from doccano/bugfix/enable-to-display-…

…non-ascii-metadata

Enable to display non-ascii metadata

Merge pull request doccano#654 from doccano/bugfix/multiline-display-…

…error

Enable to handle multiline document in sequence labeling

Merge pull request doccano#422 from CatalystCode/enhancement/mysql

Enhancement/Add support for MySQL

Add X-Frame-Options header to prevent clickjacking

Merge pull request doccano#341 from chakki-works/dev-frontend

Supporting mobile annotation