Bump to Scala 2.10.3 and SBT 0.13

This bumps the version to Scala 2.10.3 and SBT 0.13 as well as fixing every depreciation issue bar https://github.com/mdedetrich/xsbt-web-plugin/blob/767384739c40ae8d46d0bccbf69021bd0199e1c8/src/main/scala/Container.scala#L105-L106. This depreciation issue requires more work, someone else who has knows the code better should address it

Take note of https://github.com/mdedetrich/xsbt-web-plugin/blob/767384739c40ae8d46d0bccbf69021bd0199e1c8/src/main/scala/WarPlugin.scala#L74, this theoretically should work however I haven't tested it properly

Due to it fixing depreciation issues, it will likely break earlier versions of SBT