Add space-escaping to path parts of lxc.mount.entry lines in generated lxc.conf, allowing for spaces in mount point names

Fixes #2802
Format lxc_template.go with gofmt
Add explicit test strings for new escapeFstabSpaces function
Fix command line help for docker save

`docker save IMAGE DESTINATION` is not what `docker save` expects
Fix CHANGELOG: we ended up not merging the btrfs driver for last night's release
Add ParseRun unit tests
Make volumes opts more strict
Add parseRun volume unit tests
Performance of deleteImageAndChildren.

Don't walk the file system for parents each time we recurse.

Fixes #2852
Restore 'save' paragraph
Refactor attach loop device in pure Go
Move attach loop device to its own file
Extract ioctl from wrapper
Check if the target loopback is a block device
Merge branch 'master' into refactor_cgo_in_go
Remove explanation of removed argument
Rename file for consistency
Wire in pprof handlers.

Based on http://stackoverflow.com/questions/19591065/profiling-go-web-application-built-with-gorillas-mux-with-net-http-pprof
Correct comments
Merge pull request #2913 from pnasrat/2852-deleteimage-performance

Performance of deleteImageAndChildren.