Revert "add submodules: bbb-webrtc-sfu, etherpad-lite, freeswitch"

.gitmodules

-[submodule "bbb-webrtc-sfu"]
-	path = bbb-webrtc-sfu
-	url = https://github.com/bigbluebutton/bbb-webrtc-sfu
-[submodule "etherpad-lite"]
-	path = etherpad-lite
-	url = https://github.com/bigbluebutton/etherpad-lite
-[submodule "freeswitch"]
-	path = freeswitch
-	url = https://github.com/signalwire/freeswitch

bbb-webrtc-sfu @ a73429eb

-Subproject commit a73429ebb82827a6be9cfae7b22f154a47d4dcf4

etherpad-lite @ 2dbc25b9

-Subproject commit 2dbc25b90a5ea164458762154c7954cd04dadffc

freeswitch @ 133fc2c8

-Subproject commit 133fc2c870050fc7edbf79dbedec74c34f2cbfe7