utils: Add missing "B" for pretty_size()

* Add missing unit for megabytes, should print "MB".
console: Add support for displaying elapsed time

* Display the elapsed time in the the response row.
* Very handy for passive performance analysis.
console: Add support for displaying transfer rate

* Display the rate in the the response row.
* Very handy for passive performance analysis.
add travis ci
travis ci: make sure that netlib is installed from head
travis ci: fix pip install order
add jsbeautifier to requirements.txt
Merge pull request #159 from kmanna/elapsed_time

Transfer Rate and Elapsed Time Statistics
Tweak timing display

- Remove elapsed time. Space is at a premium here, and this is somewhat
redundant with the rate figure. We should display complete timing information
somewhere in the detailed flow view.
- Tone down the colour. Reserve highlights for stuff that should really pop out
to the user.
- Make rate calculation more acurate. Include header sizes. Use response start
and end time, rather than request end and response end. This means that we show
actual transfer rates, not including DNS requests and so forth.
Fix pretty_size unit tests.
Merge pull request #162 from mhils/add_travis_ci

Add travis CI
Prep for release: CHANGELOG and CONTRIBUTORS
Version bump.
add coveralls.io