Adds event loop and global event registration

Changes global variables from char*[] to char** and switches
memory allocation to match
Fixes strtok calls - previously used strtok(variable) and switched
latter calls to strtok(NULL)
Fixes execvp call
Switches sigkill error statement to match signal (was sigterm)
Fixes variable name error
Fills in keepalive function

Will attempt to send ping messages to all online clients
If nothing is written or an error is returned, will close
connection to that host
Adds basic error checking for keepalive packets
Adds basic DBus functionality

Updates Makefile to dynamically grab libraries and cflags for includes
using pkg-config
Fixes issues with DBus in relation to pthread

Adds function to set handler's PID
Fixes slight discrepancy in create_str by switching sizeof(s) to length + 1
Calls updateHandlerPID DBus function from handler

Adds boolean return value to avoid timeout from client - it appears the
no-return-value property described in the freedesktop.org DBus spec is ignored
Fixes oversight where a host will initially attempt to connect to itself
in addition to other hosts