Deal effectively with large audit_atom table

Instead of attempting to write logs and delete rows in a single pass
run loops which break the task into manageable pieces which do not run
out of memory.  Using this system even tables with tens of millions of
records can be effectively managed.
Ensure Ilios_Logger can rotate large files

Instead of attempting to read the file into memory, write it out in
much smaller chunks.
Merge pull request #613 from jrjohnson/splitauditcron

Deal effectively with large audit_atom table