Remove 'openstack/common/context.py'

context.py is not used anywhere in Glance. Consequently, we can get
rid of it.
Also, context.py is the only file left using uuidutils.

Change-Id: I657e20ac39fbace60f230652912a4bf792836206
Closes-Bug: #1253497
Remove vim header

No need to set tabstop tons of times, this can be set in your vimrc
file instead.

More disucssion:
http://openstack.10931.n7.nabble.com/Remove-vim-modelines-td21780.html

Change-Id: I3b830a5bb831a63c188109e6fad66ba48884fff3
Partial-Bug: #1229324
Merge "Remove vim header"
Merge "Remove 'openstack/common/context.py'"