The ultimate cleanup
readme update
expose only cb.h
don't add to includedir

Full path (libcbugzilla/whatever) is required to link
define version at one place
cleanup
move include to libcbugzilla
These shall not be public
+ ChangeLog
improved error handling

* return values now use CB_SUCCESS or CB_E<X> instead of EXIT_SUCCESS
and EXIT_FAILURE

* many missing return value checks were added

* no more writes to stdout/stderr from library code (providing error
return values is TODO)
sed changes for previous commit
fix init curl separately from cbi_new

* Also default value for verifyhost is 2
+ lib exmaple