they do not need to be in 3rd and 4th posstions.

Also:
* add latest_bandwidth header
* add file_created header
* fix bw files header tests
* disable tests that assume timestamp to be the file creation
time
* if we use ISO 8601 with T as separator,
  datetime format string is not needed

On one hand, for weeks now I've been running sbws and it seems to be
correctly doing downloads over tor. I've monitored existing circs and
streams with a script that queries the control port and what I saw made
sense.

On the other hand, I just tried running sbws on my laptop over a VPN
that blocks resolution of a hostname of mine. I got a proxy error with
a suspicious hostname in the message that led me to believe that
destination usability checks were not actually being done over Tor like
they are supposed to be.

The way Requests tells you to use proxies is by specifying them *not* on
the session object, but as an argument[0]. So do that.

[0]: http://docs.python-requests.org/en/master/user/advanced/#proxies

remove unused key tor_control_socket
remove duplicate key started_filepath in scanner section

GH: closes #139

Left over from sbws server days

GH: ref #143

Using MANIFEST.in would include those files in the source distribution,
but include_package_data is need to also include all of them in the
binary distribution.
The binary distrution was missing tests on others not included in
package_data.

Tests have been failing because -- I guess -- python 3.4 can't unpack
two lists in the same list of arguments.

- Create constants for the separators
- Create methods to generate the header text
- Create method to parse the header text
- Fix tests

timestamps