Add a warning to @memoized when caching is impossible

The @memoized decorator cannot cache function calls that take unhashable
arguments. So far it just ignored them, and silently called the function
directly without any cache. This commit adds a warning in such case, so
that we can see where @memoized is not really doing anything.

I used Python's warning mechanism, because we can easily configure the
particular warning to become an exception or to be ignored entirely.

Change-Id: I4b581f504972ffac589fdb78bfb9fb194d2b4525
Add a loadAngular function

    If something is added to the DOM with external tools, angular is not
aware of these changes (Ajax call, pure js DOM manipulation, etc...).
This patch add an utility function which will load angular on the given
element.
    There is also an example on modal, angular is now loaded when a
modal is shown.

Fixes bug #1258192

Change-Id: I3266b455d79d7d1856e4a622e927ed4af8e90b5e
Hide AZ when creating Volume from snapshot

Volume created from snapshot must match the AZ of the snapshot.
It doesn't make sense to allow the user to select the AZ as the
only valid values are Any AZ or AZ of the snapshot - which the user
still need to figure out.

Change-Id: Id3fb03fc2bc152ae0af72b939f63d9d403324fe6
Closes-Bug: #1257845
Initialize the table after data load in TableTab

Change-Id: Icd4b5b4f01f1ecdf54146fa70311cc873ee4d0c6
Closes-Bug: #1259226
Added help note in attach volume dialog

Added help note in Horizon's dashboard (Edit attachments dialog), in order to
inform that device name may not match the proposed one.
The intention is to provide more information when device names don't match due
to hypervisor limitations or naming convention.

Change-Id: I39828542047a2f2149815e2beba1099501aa755e
Partial-Bug: #1217874
Merge "Initialize the table after data load in TableTab"
Merge "Add a loadAngular function"
Merge "Hide AZ when creating Volume from snapshot"
Merge "Add a warning to @memoized when caching is impossible"
Merge "Added help note in attach volume dialog"
Centralizing page size code, reading cookie

Centralizing duplicate code around the default page size.
Additionally, we now read the 'horizon_pagesize' cookie set for
the user in the settings panel to reuse the value across sessions.

Closes-bug: #1251456

Change-Id: I78b6c978926f53a598f89745c517b8083270e5ba