Improve logging for functions

[Alexey Ivanitskiy]

There are some places in code, where we raise error mesages during resolve build in functions. These messages don't propogate to user and can not be used for debugging. So we should add log messages for these purposes.

[Steven Hardy (shardy)]

Note that if you want to improve the message for the user, then raising a descriptive exception is the right thing to do, as the logs are not visible to any (non developer) users.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/109333

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/109984

[OpenStack Infra (hudson-openstack)]

Change abandoned by Alexey Ivanitskiy (<email address hidden>) on branch: master
Review: https://review.openstack.org/109984

[OpenStack Infra (hudson-openstack)]

Change abandoned by Alexey Ivanitskiy (<email address hidden>) on branch: master
Review: https://review.openstack.org/109984
Reason: this patch was abandon because it has wrong Change-ID

[Angus Salkeld (asalkeld)]

The bug may be correct, but the solution is not to log. We need to make sure that exceptions make it to the user.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Angus Salkeld (<email address hidden>) on branch: master
Review: https://review.openstack.org/109333
Reason: Abandoning old reviews, feel free to repost to get it merged.