SPARK-1335. Also increase perm gen / code cache for scalatest when invoked via Maven build

I am observing build failures when the Maven build reaches tests in the new SQL components. (I'm on Java 7 / OSX 10.9). The failure is the usual complaint from scala, that it's out of permgen space, or that JIT out of code cache space.

I see that various build scripts increase these both for SBT. This change simply adds these settings to scalatest's arguments. Works for me and seems a bit more consistent.

(I also snuck in cures for new build warnings from new scaladoc. Felt too trivial for a new PR, although it's separate. Just something I also saw while examining the build output.)