[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.
[rackspace|dns] fixing DNS pagination issue #1887
Merge branch 'master' of github.com:fog/fog into dns_page
Add SimpleCov and Coveralls.io dependenices
Add rake tasks for travis, which include publishing coverage reports.
Change travis to use a rake task instead of shindont directly.
This is partly necessary for
https://github.com/lemurheavy/coveralls-ruby/pull/20, though
I'm a fan of running just "rake" or "rake travis" for simplicity
anyways.
The actual simplecov/coveralls setup.
The use of Process.pid is an attempt to avoid confusing SimpleCov when
running tests in parallel.  Other tests frameworks take a similar
approach when they detect parallel_tests.
[rackspace|dns] added total_entries attribute to zones
[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