In the past i have been using SourceTree for SourceControl. Its not bad but i prefer now perforce.
Its just the better pro tool. The perfect solution to use it with Amazon Cloud Server.
I testet it with an free year its pretty good, but expensive then.
You need to setup an linux server. Then everything runs like cake.
Perforce is for the first 20 Users free right now. For Unity is a perfect solution.
I now switch to Helix Cloud from perforce its free and also Beta.