check if disconnect plugin is installed and enabled

Change-Id: I484831cf28a2567967538c70b01e90d96a5b14e3
UI modifications to allow project deletion on gerrit

Change-Id: Id38c498b0e6874985a87e81990f5f60bf7d7a67a
make deletion into system event

Change-Id: If29640e055dab5153cd8a8bd97f493c2688d4ef3
display feedback on repo management page when project is going for deletion on Gerrit's side

Change-Id: I7f344f2b333761dcdebc01a43a41a2d64db903e6
purifying html in gerrit pane

Change-Id: I6cbd5314b4be53e57c89b5f01ca85a8d94f6a6f6
Merge remote-tracking branch 'gerrit/4720_Be_able_to_delete_Gerrit_project_on_disconnection' into tuleap-stable-master

* gerrit/4720_Be_able_to_delete_Gerrit_project_on_disconnection:
  purifying html in gerrit pane
  display feedback on repo management page when project is going for deletion on Gerrit's side
  make deletion into system event
  UI modifications to allow project deletion on gerrit
  check if disconnect plugin is installed and enabled

Change-Id: I41dafc74a91803771be4e8962bff81c52a9d6ca1
Tuleap 6.4.99.16

Change-Id: I2636742a72b3a9ba73806cb7d33da7d21da085be