Elements from within PROCS are causing problems when reading in network components.

**Describe the bug**
Constraints were given date values equal to ">" as

**To Reproduce**
Steps to reproduce the behavior:
The following data in the network file would cause the problem when reading in the constraints using a model.network.constraints.get_all().
NexusConstraint(name='WELL1', date='>', max_surface_liquid_rate=6100.7)

```
TIME 04/10/2019

PROCS NAME PROCNAME
IF(TIME > 0.0) THEN
DO something
ENDPROCS

CONSTRAINTS
WELL1 QOSMAX 6100.7
ENDCONSTRAINTS
```

**Expected behavior**
Content within PROCS routines should be ignored for now.
the constraint should be NexusConstraint(name='WELL1', date='04/10/2019', max_surface_liquid_rate=6100.7)