Reuse exceptions from Oslo

- Remove unused exceptions from novaclient.exceptions
- Reuse exceptions from common code

OpenStack clients which already use exception from common code:
- ironicclient   - I784007f36dd6a63fc4c77e0d0f0f000e05eb792f
- keystoneclient - Iedf4e5d753d4278d81751ba0f55fdef3566b56de
- saharaclient
- tuskarclient   - Iacbf219168fae62d864c6594dd41e0737e848cfa

Similar patches in other clients related to reusing exceptions
from common code:
- cinderclient   - I07f04ba5357e0196fe43b510e1d2fff5afa02faa
- glanceclient   - I9838391cff7e450f08d27668564b02e63259186c

Related to blueprint common-client-library-2

Change-Id: Ia35d65d57a0047f88a609070f8b4c76215cbd3e9
Deprecate num-instances in favor of min/max count

For 'nova boot', num_instances only set max_count, which will try to
launch up to max_count instances. But sometimes users want to either
launch min_count instances or nothing. So deprecate --num-instances
and use --min-count and --max-count instead.

DocImpact: deprecate '--num-instances' for 'nova boot'

Change-Id: If0088aef554a528258799b22c6e793541474cb0d
Closes-bug: #1309244
Remove duplicate test test_boot_multiple

test_boot_multiple is a duplicate if test_boot_num_instances.

Change-Id: I03a4def85b79109e6a950587542b53741b06bd70
Make port-id and net-id keys mutually exclusive

These keys are never used together, and port-id always takes precedence
in Nova API when present. This patch makes these parameters mutually
exclusive and updates help strings accordingly.

Change-Id: I207dc637cb69d9ab3ff6024a657d2c1890057b4d
Closes-Bug: #1314097
Add extension-list command for v3 API

Nova returns available extension list through its REST API.
The command of v2 API has been implemented, and this patch adds the
one of v3 API.

Note:
The command name of v2 is "nova list-extensions" but the one of v3,
which this patch adds, is "nova extension-list" because the name fits
to the other command names.

Change-Id: Ibee712b0aa5898a94e362f20be71e8863500b195
Allow the default value of 1 to  be set for boot multiple

Allow one to call the following with their default values of 1:
* nova boot --num-instances 1
* nova boot --min-count 1
* nova boot --max-count 1

Don't allow min_count>max_count.

This is the only place where if a user passes in the default value the
CLI will return an error.

Change-Id: I805b3f0c778e9c70c5817624fb696a746dfe3d5b
Merge "Deprecate num-instances in favor of min/max count"
Merge "Remove duplicate test test_boot_multiple"
Merge "Allow the default value of 1 to  be set for boot multiple"
Merge "Add extension-list command for v3 API"
Merge "Make port-id and net-id keys mutually exclusive"
Merge "Reuse exceptions from Oslo"