[GH #927] Added tests for sort() method of ResizableFloatArray PMC
[GH# 927] Test output more specific wrt how float array was resized
[GH #927] Test sort() after unshift in ResizableFloatArray

It's probably a good idea to check if sorting after an unshift works as well
as the currently available tests for simply sorting and for sorting after a
push.  This way we test the interaction between resizing and sorting.
Merge pull request #947 from paultcochrane/ptc/resizable_float_array_sort_test

Added tests for sort() method in ResizableFloatArray PMC