Update src/cxtracker.c

Added ability to roll off disk when free disk space is less than n bytes.

Added ability to store pcaps to disk in directories named YYYY-MM-DD.

Note: Roll-off is currently recursive, in case we want to extend directory tree later or the user wants to group directories by week / month / etc in a modification, outside script, or by hand.

It looks at directories alphabetically but the files by age.  I'm not sure if I'm fine with the inconsistency or not.  Initial feeling is yes, because user may want to alter the directories.
Update src/cxtracker.c

Fixing issue https://github.com/wmesser/cxtracker/issues/1
-A now prints the right message on run.
Update src/cxtracker.h

Increasing snaplen.
Update src/cxtracker.c

Moved pruning to be done on disk write.
Update src/cxtracker.c

Fixing issues 6 & 7
Create COPYING

In response to: https://github.com/gamelinux/cxtracker/issues/20
Update doc/INSTALL

In response to https://github.com/gamelinux/cxtracker/issues/15
Update bin/cxtracker2db.pl

Merging https://github.com/gamelinux/cxtracker/commit/e1837f74bcb4462d6c98acf695676da00746aac1
Update src/cxtracker.c

Fixing issue #8
Update src/cxtracker.c

Added error message when failing on prune.
Update src/cxtracker.c

Minor tweak.
Update src/cxtracker.c

Fixed issue #7
Update src/cxtracker.c

Fixing compiler warning "warning: ‘rollover_names’ defined but not used"
Update src/cxtracker.h

Fixing compiler warning "warning: ‘rollover_names’ defined but not used"
Update bin/cxtracker2db.pl

Attempting to resolve Issue 11.
Update bin/cxtracker2db.pl

Fixing file rename issue.
Update src/cxtracker.c

Fixed the possibility of a FDIR placed in the pcaps directory as part of cxtracker2db.pl being pruned by cxtracker.c
Update doc/INSTALL

Cleaning up docs a bit.
Update doc/README

Cleaning up docs a bit.
Update bin/cxtracker2db.pl

Tweaked spelling.