Switch to Qt 5.7 (RedisInsight#3718)

* Switch to Qt 5.7

* Update configure

* Update .travis.yml

Fix regression in Connections Tree

NS context-menu doesn't open Bulk Operations Dialog

Fix regression in connection tree module (RedisInsight#3674)

Fix issue RedisInsight#3666

Update qredisclient

Bump version in appveyor

Update appveyor.yml

Update appveyor.yml

Merge pull request RedisInsight#3624 from defmys/0.8.0

fix bug: renameKey, removeKey and setTTL only affects the 1st tab.

Fix issues in New Key dialog

Merge pull request RedisInsight#3521 from uglide/0.8.2

Merge fixes for 0.8.2