Review spy messages, make them more useful to the user

[algorys]

Review spy messages, make them more useful to the user.

Now:

'HOSTNAME is STATE. There are some services STATE'
# or
'HOSTNAME is STATE. You've nothing to do'

Not very useful...

Expected:

# For hosts
'HOSTNAME is STATE (LAST_CHECK)'
# If the host state has changed since the last message, be more specific:
'HOSTNAME state have changed: STATE ! (LAST_CHECK)'
# Or
'HOSTNAME is UP. All service are OK, acknowledged or downtimed. (LAST_CHECK)'
# For services
# With the icon color that will depend on the state.
'Service SERVICE_NAME of HOSTNAME is STATE'
# If service state has changed since the last message, be more specific:
'Service SERVICE_NAME of HOSTNAME state have changed: STATE !'

[algorys]

Done.