Split the new file utilities into a separate runtime file.

qio.c was quickly going to run out of control with all the new file operations
in it, and qio wasn't necessarily the right place to put them so now these
operations will live in their own .c/.h file: chpl-file-utils.
Split new file utilities from IO.chpl to FileUtils.chpl

IO.chpl would quickly get out of hand if the new file operations were to live
there any longer, so I put them in a separate file, FileUtils.chpl.  The string
path operations, when they are developed, will live in PathOps.chpl
Forgot to update the module order tests.
Revert "Forgot to update the module order tests."

This reverts commit fe982c8a8fcfcce4344678418b346dec9bd6cef1.

Brad pointed out (and I agree, in retrospect) that the FileUtils module
shouldn't be used unless specified by the user, so updating these tests is
unnecessary.
Take comments into account.

Rename FileUtils to FileSystem, and make it only included when the code
specifically uses that module.  As a result, added a use call to all the tests
of file utilities.  Renamed the C interface files from chpl_file* to chpl_fs*.
Merge branch 'master' into splitFileFiles
Merge pull request #576 from lydia-duncan/splitFileFiles

Split IO.chpl and qio.c/.h into smaller portions [reviewed by bradc, fsouza]

This moves the recent file utilities work into its own module file and
runtime support files.  This module will only be used when specified
by a use call, so the test files needed to be updated to include this
line.