Modified getHostname, getFQDN and getCPU to utilize regEX

Modified the three above methods to use regex, should be much more efficient than the 3000 lines of string and list splitting.

still works as expected
```bash
$ python core/main.py -i veos-03 -m arista -f getFacts
{   'connect_ip': 'veos-03',
    'cpu_utilization': u'2.2%',
    'free_system_memory': 57532,
    'hostname': u'veos-03',
    'platform': u'vEOS',
    'serial_number': '12345',
    'system_uptime': u' 3:45',
    'total_sytem_memory': 1000444,
    'var_name': 'dev',
    'vendor': 'arista',
    'version': u'4.12.1-1581426.vEOS4125.1 (engineering build)'}
```