add toolip for assignee infomation  on issue list
Merge pull request #421 from insanehong/issue/assigned-tooltip

Fix #414  -  add toolip for assignee infomation  on issue list
change link color(RGB4183c4) on README area
Merge pull request #422 from insanehong/issue/link-color

change link color(RGB4183c4) on README area