datetime_tz isn't readily available, so it's a lot easier to just
package it within the nilmdb tree.

Now nilmdb.client, nilmdb.server, nilmdb.cmdline, and nilmdb.utils
are each their own modules, and there is a little bit more of a
logical separation between them.  Various changes scattered throughout
to fix naming (for example, nilmdb.nilmdb.NilmDBError is now
nilmdb.server.errors.NilmDBError).

Reduced usage of "from __future__ import absolute_import" as much
as possible.  It's still needed for the functions in the nilmdb/server
directory to be able to import the nilmdb module rather than the
nilmdb.py script.

This should hopefully ease future packaging a bit.

There's some bug with the testing harness where placing e.g.
  from du import du
in nilmdb/utils/__init__.py doesn't quite work -- sometimes the
module "du" replaces the function "du".  Not exactly sure why;
we work around that by just renaming files so they don't match
the imported names directly.

git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@10709 ddd99763-3ecb-0310-9145-efcb8ce7c51f

git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@10655 ddd99763-3ecb-0310-9145-efcb8ce7c51f

Add "end" parameter to TimestamperRate, to force the file to end
before a specific time.  Will be good for loading in old files and
knowing that things don't overlap.


git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@10644 ddd99763-3ecb-0310-9145-efcb8ce7c51f

go away if it gets packaged in Debian etc.

Add nilmdb.timestamper classes

Start test_timestamper (needs work)

Number the functions in test_client so they run in the right order to
leave the database in a good state.

Fix some brokenness with module importing and namespaces



git-svn-id: https://bucket.mit.edu/svn/nilm/nilmdb@10643 ddd99763-3ecb-0310-9145-efcb8ce7c51f