Logging error if cookie size is > 4KB

When session storage is configured to use signed cookies, logging error when
cookie size is > 4KB.

Change-Id: Ia766f4505ce0527123a9fa9a62bf6d312858da46
Closes-Bug: #1214197
Set Keypair create button disabled when quota exceeded

We should disable create button when quota exceeded like creating instances.

Change-Id: I9cd044c195ccc1160f7d5cb0ee24fc346669d4d7
Fixes: bug #1250825
Add missing __contains__() and get() methods to QuotaUsage

The QuotaUsage class was missing __contains__() and get() methods which was
causing unexpected behaviour, e.g:

    >>> usages = quotas.tenant_quota_usages(request)
    >>> 'ram' in usages
    False
    >>> usages.get('ram')
    None

Change-Id: Ib0b1ad69c4bf4effd7c10827d23bcc713bdc5ed6
Merge "Set Keypair create button disabled when quota exceeded"
Merge "Add missing __contains__() and get() methods to QuotaUsage"
Merge "Logging error if cookie size is > 4KB"