Unnecessary validation of numeric fields forces user to manually enter even default values when configuring infinispan subsystem

Description of problem:
Various forms related to infinispan configuration have numeric fields validation which requires valid (nonempty) numeric value even for attributes with default values. This behaviour forces user to manually enter even default values.

Version-Release number of selected component (if applicable):
HAL 2.5.6.Final-redhat-1

How reproducible:
always

Steps to Reproduce:
1. start EAP 6.4.2
2. in web console go to Configuration -> Subsystems -> Infinispan -> Cache Containers
3. click 'add' button
4. enter new container name let's say 'testcontainer', click 'save'
5. select 'testcontainer' in 'Cache Containers' table, select 'transport' tab, click 'edit'
6. check 'is transport defined', enter 'teststack' as stack name, click 'save'

Actual results:
not saved, Invalid numeric value warning under 'Lock Timeout' field

Expected results:
successfully saved, default value of 240000 ms shown in 'Lock Timeout' field