Merge branch 'release-0.14'
Bump version to 0.15rc1

Add multiple version files to automatically update the docs version too.
We need devflow 0.13rc1 or later for this to work
Update ChangeLog for version 0.15rc1
Add pithos backend version check

Synnefo version 0.15.1 has introduced a selectable storage backend
for Pithos, resulting in necessary changes to the ModularBackend class.
In order to keep backward compatibility with older Synnefo versions,
we check the Pithos backend version and instantiate the ModularBackend
class appropriately.
Bump version to 0.15rc2

Update Changelog and version files.
pithcat: Remove default option values

Handle better possible backend options and require necessary
ones by printing appropriate error messages.
Fix typos in error messages and docs

Replace all references of `environmental variable' with `environment
variable'
Bump version 0.15rc3

Update ChangeLog and version files
Merge branch 'release-0.15'
Bump version 0.15

Update ChangeLog and version files for snf-image 0.15
Bump version to 0.15next
Bump version to 0.15.1
Fix a typo in the program name
Remove support for OS API version 5, 10 and 15

snf-image wasn't working correctly with API versions prior to 20 anyway.
Source the variant file in the verify script

If the variant file has defined mandatory input variables like IMG_ID
the verification script should not fail to find them.

This fixes #35
Make img_passwd os parameter optional

If the parameter is not defined then the ChangePassword task will not
run at all.

This resolves #34
Fix a typo in HYPERVISOR variable substitution

Many thanks to Brian Candler https://github.com/candlerb for pointing
this out. This fixes #39
Give priority to command line os parameters

OS Parameters defined as command-line arguments should overwrite the
ones given in the variants file.

Many thanks to Brian Candler https://github.com/candlerb for the
suggestion and all the help.
docs: Reflect the changes made in the hotfix

* Remove obsolete parts from the /etc/default/snf-image sample file
  shown in the configuration section.
* Update the documentation about having made the img_passwd an
  optional parameter.
Update changlog and version files for ver 0.15.1