Provide default name length & type for ComputeResource entities

[abalakh]

Default name length for AbstractComputeResource (and subentities like LibvirtComputeResource) was not set, which can lead to entities with one character in name being created, which in rare cases (like latest automation run 😄 ) can attempt to create 2 entities with the same name (the longer name is, the less is the chance of the same name generation).
Also removing cjk from the tuple of acceptable string types as it creates issues with readability and basically increases efforts for debugging.
This PR should have been implemented as a part of #290

[abalakh]

Not sure if some kind of test results are needed here, but just in case:

>>> entities.LibvirtComputeResource().create(True)
2017-01-30 17:47:48 - nailgun.client - DEBUG - Making HTTP POST request to https://example.redhat.com/api/v2/compute_resources with options {'verify': False, 'auth': ('admin', 'changeme'), 'headers': {'content-type': 'application/json'}} and data {"compute_resource": {"name": "bFfrTiRPtz", "provider": "Libvirt", "url": "http://XVZAvDyqHY.info", "display_type": "vnc"}}.
2017-01-30 17:47:50 - nailgun.client - DEBUG - Received HTTP 201 response: {"description":null,"url":"http://XVZAvDyqHY.info","created_at":"2017-01-30 15:47:51 UTC","updated_at":"2017-01-30 15:47:51 UTC","id":2,"name":"bFfrTiRPtz","provider":"Libvirt","provider_friendly_name":"Libvirt","display_type":"vnc","set_console_password":true,"images":[],"compute_attributes":[],"locations":[],"organizations":[]}
nailgun.entities.LibvirtComputeResource(nailgun.config.ServerConfig(url='https://example.redhat.com', verify=False, auth=('admin', 'changeme')), description=None, url=u'http://XVZAvDyqHY.info', provider_friendly_name=u'Libvirt', location=[], provider=u'Libvirt', organization=[], display_type=u'vnc', id=2, set_console_password=True, name=u'bFfrTiRPtz')
>>> entities.DockerComputeResource().create(True)
2017-01-30 17:48:16 - nailgun.client - DEBUG - Making HTTP POST request to https://example.redhat.com/api/v2/compute_resources with options {'verify': False, 'auth': ('admin', 'changeme'), 'headers': {'content-type': 'application/json'}} and data {"compute_resource": {"provider": "Docker", "url": "unix:///var/run/docker.sock", "name": "eKGnAatz"}}.
2017-01-30 17:48:17 - nailgun.client - DEBUG - Received HTTP 201 response: {"description":null,"url":"unix:///var/run/docker.sock","created_at":"2017-01-30 15:48:17 UTC","updated_at":"2017-01-30 15:48:17 UTC","id":3,"name":"eKGnAatz","provider":"Docker","provider_friendly_name":"Docker","user":null,"images":[],"compute_attributes":[],"locations":[],"organizations":[]}
2017-01-30 17:48:17 - nailgun.client - DEBUG - Making HTTP GET request to https://example.redhat.com/api/v2/compute_resources/3 with options {'verify': False, 'auth': ('admin', 'changeme'), 'headers': {'content-type': 'application/json'}} and no data.
2017-01-30 17:48:17 - nailgun.client - DEBUG - Received HTTP 200 response: {"description":null,"url":"unix:///var/run/docker.sock","created_at":"2017-01-30 15:48:17 UTC","updated_at":"2017-01-30 15:48:17 UTC","id":3,"name":"eKGnAatz","provider":"Docker","provider_friendly_name":"Docker","user":null,"images":[],"compute_attributes":[],"locations":[],"organizations":[]}
2017-01-30 17:48:17 - nailgun.client - DEBUG - Making HTTP PUT request to https://example.redhat.com/api/v2/compute_resources/3 with options {'verify': False, 'auth': ('admin', 'changeme'), 'headers': {'content-type': 'application/json'}} and data {}.
2017-01-30 17:48:18 - nailgun.client - DEBUG - Received HTTP 200 response: {"description":null,"url":"unix:///var/run/docker.sock","created_at":"2017-01-30 15:48:17 UTC","updated_at":"2017-01-30 15:48:19 UTC","id":3,"name":"eKGnAatz","provider":"Docker","provider_friendly_name":"Docker","user":null,"images":[],"compute_attributes":[],"locations":[],"organizations":[]}
nailgun.entities.DockerComputeResource(nailgun.config.ServerConfig(url='https://example.redhat.com', verify=False, auth=('admin', 'changeme')), description=None, url=u'unix:///var/run/docker.sock', location=[], email=None, provider_friendly_name=u'Docker', user=None, provider=u'Docker', organization=[], id=3, name=u'eKGnAatz')

[coveralls]

Coverage remained the same at 98.583% when pulling b464ee6 on abalakh:def_name_abst_cr into 26c0239 on SatelliteQE:master.

[rplevka]

ACK - requires cherry-picks

[rochacbruno]

ACK

pending cherry picks

[abalakh]

Part of #368