Update buck to the latest version

This version includes a lot of new features and improvements.
The highlights are:

* Switched to top-down-building, which should generally make builds
faster. The old behavior can be bypassed by passing --deep on the
command line: [1]

* New query command was added (inspired by Bazel): [2]

* Performance improvement in file globbing

Extend tools/eclipse.py to pass the --deep option to ask Buck to
execute bottom-up build when generating the Eclipse project. This is
needed otherwise after using the buck clean command only the top rule
artifact would be fetched from the cache and the buck-out/gen/lib
folder would remain empty.

To allow two genrules, located in the same BUCK file, to have the same
output artifact name, genrule output is namespaced with genrule name:
[3]. That why switching to new Buck version requires buck clean.
Otherwise the build would fail: [4].

[1] https://github.com/facebook/buck/commit/217cec33bcd0b0eb7ebd0c444938495379267d60
[2] https://buckbuild.com/command/query.html
[3] https://github.com/facebook/buck/commit/c92ef212b53fff08a8452649b4d4faadc6b89b11
[4] http://paste.openstack.org/show/468992

Change-Id: If336ea86970dd95e3af13b92e7665ecaef369105