0.8.8

Thank to various contributions from Guake users, I am happy to announce a new minor fix release of
Guake.

Features:

• Close a tab with the middle button of the mouse

Bug Fixes:

• Fix error when toggle key was disabled
• Update change news
• Uppercase pallete name
• Fix pylint errors
• Convert README badge to SVG
• Update Japanese translation
• update Russian translation
• updated CS translation
• Update zh_CN translation