removed unused logger and get_task_logger
removed more logger.exception and replaced it with heka.raven calls
reuse the existing self.heka_client bound to all DatabaseTasks
replaced get_client calls with self.heka_client in ichnaea.tasks
Break out earlier in error reporting and report only one error at a time.

We get some requests that have a systematic error in each batch item,
so before we reported 100 errors at a time. The combined error message was
too long for the heka message. Even though it's only debug messages, we got
`Error sending message (error(90, 'Message too long'))` including the full
message spewed out on stderr.
Merge pull request #109 from tamcap/master

Minor update to submit.rst
Merge pull request #110 from crankycoder/features/104-raven-exceptions

Features/104 raven exceptions
capture and send exceptions inside task execution via raven, refs #104
update dependencies to latest versions
Update pyramid to latest version.

zpt/mako support is no longer part of the core and needs to be
installed / configured explicitly.
update celery and its dependencies to latest versions
Use the new bindparams method for sqlalchemy text clauses.

This lets sqlalchemy take care if proper escaping/quoting of variables.
avoid integrity errors on duplicate stat task execution
Avoid sending raven messages for all malformed client requests.

Amazingly speeds up tests by 10% - though at 5 seconds it's hard to tell :)
simplify create/process wifi measure code with single entries list, refs #98
simplify create/process cell measure code with single entries list, refs #98
stop maintaining created column in measure table, refs #98
drop no longer needed index on measure.created column, refs #98
stop maintaining radio field in measure table, refs #98
clarify `id` entry in cell/wifi records, refs #98
factor out cell/wifi insert task call from process_measure, refs #98