Include next link when default limit is reached

The /servers and /servers/detail APIs support pagination and a
"next" link should be included when more data is available, see
http://docs.openstack.org/api/openstack-compute/2/content/
Paginated_Collections-d1e664.html. In the documentation it states
that 'collections are required to contain atom "next" links'.

When the default "osapi_max" limit is reached then the "next" link
is not included in the API reply. In this case, the caller cannot
determine if there are any more servers and has no marker value
such that they can retrieve the rest of the servers.

For example, assume that there are 1050 VMs and the osapi_max value
is the default of 1000. The /servers API will return the first 1000
VMs but it will not include the "next" link; the caller has no way
to determine if there are more then 1000 VMs and no way to retrieve
the other 50 VMs.

The fix for this is to include the "next" link when the number of
servers being returned is the maximum limit, even if the "limit"
parameter is not supplied. Note: the caller could workaround this
by specifying the exact "osapi_max" limit value (ie, limit=1000)
on the API call but this requires that the caller knows the
configured limit.

Change-Id: I9b3da852b0ab11dc980524e2317ee876a3ec28b8
Closes-bug: 1288466
(cherry picked from commit 968c01afe7ff43346f5817e2a3adf97fd03106b1)
Catch missing Glance image attrs with None

Glance is known to drop values from its response if they don't resolve to true.
 Previously in I67b7dd16a94fe60d873c012f6bd246ab24500d5a the None catch was
 removed as this WILL cause a call to glance for missing value and
 optimizations where made to attempt to pre-cache values that can be missing
 in expected ways. However there are still situations that can't be optimized.

Notably this can occur with disk_format, container_format, name, deleted,
 and checksum.

Test adapted from I85c42f8351763da201021a22f5ff0ebd62c6b2db by Mike Perez

Closes-bug #1308058
Co-Author: Mike Perez <thingee@gmail.com>

Change-Id: Icddead6f746d4d3ba652858eaae425acce8c177d
(cherry picked from commit ef3f158a5aa1988be8ab2f295252373f3ee85809)
Merge "Include next link when default limit is reached" into stable/icehouse
Merge "Catch missing Glance image attrs with None" into stable/icehouse