[openvz] Fixes #1871 test helper callback

This moves the setting up of an `at_exit` callback from when the file
is required to when the matching helper is used.

This prevents it failing on any run where OpenVZ is excluded.
Fix autoincrement when creating a flavor if private flavors exist.

Before, only public flavors were considered when finding the next free ID. That could lead to the case where the calculated ID was already taken which lead to a conflict. This happened whenever the user tried to create a private flavor via fog and then another (private OR public) flavor afterwards. Now, we also take private flavors into account, so the conflict cannot happen anymore.

As a side effect, it is now also possible to just return all private flavors, using the :is_public => false filter on the list_flavors_detail API call or the flavors collection.
[rackspace|dns] fixing DNS pagination issue #1887
Merge branch 'master' of github.com:fog/fog into dns_page
[rackspace|dns] added total_entries attribute to zones
Merge pull request #1894 from cloudbau/flavor_id_fix

Fix autoincrement when creating a flavor if private flavors exist.
[rackspace|dns] adding :limit => 100 to clarify that all returns a limit of 100 records per page at @rupakg suggestion.
Merge branch 'master' of github.com:fog/fog into dns_page
[digitalocean] Rename do to docean in examples

Avoids using a reserved word, and `docean` is also used elsewhere in
the getting started guide.
Initial documentation for using Fog with CloudSigma.
Merge pull request #1901 from blom/patch-1

[digitalocean] Rename do to docean in examples
Fixed typos.
Update excon dependency to version ~>0.25.0
Merge pull request #1895 from rackspace/dns_page

[rackspace|dns] Fix Pagination in DNS
Merge pull request #1904 from sferik/update_excon_dependency

Update excon dependency to version ~>0.25.0
[vsphere] fix regex typo
Merge pull request #1908 from domcleal/regexp-typo

[vsphere] fix regex typo
Merge pull request #1872 from fog/fix_openvz_global_callback

[openvz] Fixes #1871 test helper callback
Merge pull request #1897 from maxlinc/code_coverage

Code coverage
[Brightbox] Updates to add collaborations

Adds requests and models for collaborations