Truth is out and IT´S OFFICIAL: The „Jerusalem Post“ openly and finally admits:
„Israel has opened its borders with Syria in order to provide medical treatment to Nusra Front and al-Qaida fighters wounded in the ongoing civil war, according to The Wall Street Journal.“
Thank you, so it´s no longer a „conspiracy theory of Assad supporters“:
http://www.jpost.com/Middle-East/Report-Israel-treating-al-Qaida-fighters-wounded-in-Syria-civil-war-393862

Update April 26th, 2015:
„Since the Nusra Front took over a key checkpoint in the Golan in the summer, it has not gone unnoticed by Arabs that Nusra has completely avoided attacking Israeli military targets in the region. The Qunaitra crossing stands between the Israeli-occupied and the Syrian-controlled sectors of the Golan – Nusra has held it since August.

UN peacekeepers have observed regular contacts between Nusra forces in the area and the Israeli troops stationed on the other side of the ceasefire line (Israel has illegally occupied part of the Golan since 1967). They also observed cargo of an unknown nature passing between the two sides from the Israelis.

More recently, when an army spokesperson talking to the Wall Street Journal confirmed Israel’s aid to al-Qaeda, it was shown that it also took the form of treating Nusra fighters in Israeli field hospitals near the ceasefire line and then sending them back to fight against the government of Syria. (Some defenders of Israel have claimed this is no different from how it supposedly treats any enemy fighter in its hospitals. But there is a crucial difference: fighters from Hamas or Hizballah captured by Israel would be sent straight to jail after hospital discharge.)“
http://richardedmondson.net/2015/04/16/the-unveiling-of-israels-hidden-alliance-with-al-qaeda-in-syria/

Update 2, April 27th, 2015:
„Israel has arrested a Syrian Druze man who documented contact between Israel and al-Nusra Front.“
http://www.aljazeera.com/news/2015/04/curious-case-israel-al-nusra-facebook-spy-150420082913157.html