Adding Swift Temporary URL support

Temporary URLs allow a user to sign an object URL with a shared
secret to so that the object can be downloaded without auth for
a specified amount of time.

http://docs.openstack.org/trunk/config-reference/content/object-storage-tempurl.html

Change-Id: Ife0b6c98c975e074d4dad0a31145573b784747c5
Allow to specify storage policy when uploading objects

Client already supports -H/--header option when creating container
or uploading objects. This patch extends this option to support
Storage Policy.

e.g.,
    swift post con -H 'X-Storage-Policy:p1'
This creates one container 'con' with storage policy 'p1'.

    swift upload con obj -H 'X-Storage-Policy:p2'
This creates container 'con' with storage policy 'p2' and uploads
object 'obj' into it.

Also fixes segmented uploading to non-default storage policy container

When uploading large objects with segmentation to container with
non-default storage policy, there will be another 'xxx_segments'
container created, but with the default storage policy. This
results all the segments to be stored with the wrong policy.

This patch is for the Storage Policy feature, and also
compatible with old versions w/o Storage Policy support.

Change-Id: I5c19e90604a0bcf2c85e1732b8a0b97ae6801994
Merge "Adding Swift Temporary URL support"
Merge "Allow to specify storage policy when uploading objects"
Fix context sensitive help for info and tempurl

Make it so that swift <cmd> --help will print the info
subcommand help for info and tempurl just like all the
other subcommands.

Also add unit tests to verify subcommand help.

Change-Id: Id3666dcf72a9727fbfda2f74c23293ada1c53aa0
Add a tox job for generating docs

Add a tox job to make it easier for developers to generate their
own docs before submitting a patch.

Change-Id: I86dbfc64a9d174697048c254c6d3d042a62350b4