astakosclient: Separate public/private POST /tokens

Introduce function authenticate(), which performs POST /tokens in
private mode, i.e. giving a token to be checked for authentication.
Function get_endpoints() performs the call in public mode, in order
to retrieve the endpoints.

Initialize endpoints lazily: when a URL is missing, get_endpoints()
is triggered.
astakos: Remove call GET /authenticate

Use POST /tokens to authenticate. Delete AstakosClient.get_user_info()
and replace its uses by AstakosClient.authenticate().
upgrade-notes: Add note for new 'ASTAKOS_AUTH_URL'
Trim trailing slash from ASTAKOS_AUTH_URL

Endpoints no more end in slash.
Fix pep8 errors
Merge branch 'feature-astakosclient-auth-url' into develop
pithos: Fix test
cyclades: Add snf-manage subnet-update

* Add snf-manage subnet-update. For the time being only the name of
subnet can be updated.
cyclades: Fix output of port-inspect command
cyclades: Various fixes to networks/subnets/pools

* Fix IP pools of subnets to take into account the 'offset' when searching
if a pool contains an IP address and when converting from value to index
and from index to value.
* Fix the way subnets are created from 'logic/networks'
* Rename 'validate_network_params' function to 'validate_subnet_params'
  and move it from 'networks' to 'subnets' packages.
cyclades: Fix reconciliation for network and pools

Fix reconciliation to work with multiple IP pools per network:
* Fix reconcile-networks command to check if a reserved_ip in a Ganeti
  network is reserved in the pool that contains this IP (if any)
* Fix reconcile-pools to reconcile each of the networks IP pools and
  take into account only those IP address that are contained in the
  pool.
cyclades: Fix subnet-list management command

Remove stale imports
cyclades: Improve subnet-list management command

Remove unnecessary functions.
cyclades: Fix tests for ports

* Mock GanetiRapiClient
* Fix some wrong checks about response codes
* PEP8 fixes
cyclades: Fix bugs in IP pools

Fix default value for 'external' argument of release_address method of
Network model. Also fix how is checked whether an IP pool contains an
address.
cyclades: Make tests work with multiple IP pools

Refactor tests so that they are aware that a network can have multiple
IP pools. Also, add extra check to PoolManager methods in order to check
whether a value is contained in the pool.
cyclades: Fix default values for IP pool

Temporary commit to change default offset and size of IPPoolTable
factory.
snf-deploy: Enable file disk template
pithos: Fix calling AstakosClient in reconcile

Do not pass service token in AstakosClient calls.
cyclades: Common module for pretty-printing

Create common module for pretty-printing database objects. Currently it
contains only functions for pretty-printing networks and ports.