recreate the scout history file if it exists but is zero length

If a server running the scout client fills it's disk, scout will
write a zero length history file. Upon obtaining additional disk
space or freeing up space by deleting files, this ensures that
the Scout client will continue checking in without manual
interaction (removing the history file to force it's recreation).
testing in progress
reverting command debugging
Only connecting to AR once, added history file to test/ folder and ignored
More tests
Merge branch 'master' of git://github.com/eric/scout-client into eric/master
Merge branch 'master' of git://github.com/jnewland/scout-client into jnewland/master
cleaned up test file a bit
scout checks in on install
added more integration tests
fixed error message when config file can't be created
Agent communicates whether or not it's running in interactive mode
version bump to 5.1
counter should multiply per-second data by 60 to get per-minute data (jnewland)
updated changelong / version
Added backtrace to compile errors
Version bump
Removing JSON pure, adding debuging
Updated vendored json_pure
Updates to json