Remove foreign key which is not supported by code

Remove foreign key which is not supported by code

The foreign key we fixed in the VNF_RES_CUSTOM_TO_VF_MODULE_CUSTOM
table is blocking distribution of the model.  The insert that's
failing is:

insert into VNF_RES_CUSTOM_TO_VF_MODULE_CUSTOM (
	VNF_RESOURCE_CUST_MODEL_CUSTOMIZATION_UUID,
	VF_MODULE_CUST_MODEL_CUSTOMIZATION_UUID)
	values (?, ?);

The error is: "foreign key constraint fails"

Issue: SO-180
Change-Id: I8d98bde144eb666430632b6089d8d27d66527884
Signed-off-by: Rob Daugherty <rd472p@att.com>