tidying up using a decorator instead for freezing objects, adding to fsig too

2 jobs for master in 13 seconds (queued for 5 seconds)
Name Stage Failure
failed
python_2 Test There is an unknown failure, please try again
    import pykat.finesse as finesse
File "/builds/finesse/pykat/pykat/finesse.py", line 83, in <module>
from pykat.node_network import NodeNetwork
File "/builds/finesse/pykat/pykat/node_network.py", line 21, in <module>
from pykat.components import Component, NodeGaussSetter
File "/builds/finesse/pykat/pykat/components.py", line 40, in <module>
from pykat.freeze import canFreeze
ImportError: No module named freeze
ERROR: Build failed: exit code 1
failed
python_3 Test There is an unknown failure, please try again
    import pykat.finesse as finesse
File "/builds/finesse/pykat/pykat/finesse.py", line 83, in <module>
from pykat.node_network import NodeNetwork
File "/builds/finesse/pykat/pykat/node_network.py", line 21, in <module>
from pykat.components import Component, NodeGaussSetter
File "/builds/finesse/pykat/pykat/components.py", line 40, in <module>
from pykat.freeze import canFreeze
ImportError: No module named 'pykat.freeze'
ERROR: Build failed: exit code 1