Merge pull request #1520 from xuwei-k/refactoring ...

some refactoring

Merge pull request #1521 from xuwei-k/test-MySQL-version ...

update MySQL v5_7_latest in test

Merge pull request #1522 from xuwei-k/Class-newInstance-deprecated ...

s/newInstance()/getDeclaredConstructor().newInstance()

Merge pull request #1517 from kounoike/pr-fix-1516 ...

Fix #1516 send noimage.png if user is removed.

s/newInstance()/getDeclaredConstructor().newInstance() ...

java.lang.Class#newInstance deprecated since Java 9

http://download.java.net/java/jdk9/docs/api/java/lang/Class.html#newInstance--

update MySQL v5_7_latest in test ...

v5_7_10 does not work Sierra

https://github.com/wix/wix-embedded-mysql/blob/wix-embedded-mysql-2.1.4/src/main/java/com/wix/mysql/distribution/Version.java#L86

use "exists" instead of "find().isEmpty"

use "contains" instead of "find().isEmpty"

use "contains" instead of "find().isDefined"

use exists instead of "filter().nonEmpty"

remove return

use count instead of "filter().length"

remove .get

use "Map#getOrElse" instead of "get().getOrElse"

use switch

use "contains(key)" instead of "exists(_ == key)"

use "forall" instead of "filterNot().isEmpty"

Remove message on sign-in dialog. and change message in System settings.

Add caution message in System settings.

When using H2, caution message shows at sign-in.

Fix #1516 send noimage.png when user is not exist or removed.

(refs #1511)Fix bug in updating group information

Delete duplicate css style

Fix broken diffstat layout at zoom in/out

Merge branch 'master' into feature/plugin-hotdeploy

Added Plugin.uninstall() method to cleanup, but remove for now

Fix error message

Check plugin duplication

Merge pull request #1497 from kounoike/pr-textavatar ...

Add support auto-generated icon for default avatar.

Different style of avatar for groups.