Update phonenumber dependency

This is to avoid https://github.com/nvie/pip-tools/issues/50 so that
pip-compile (from pip-tools' future branch) can be used to pin
dependencies. See also http://nvie.com/posts/better-package-management/.
Bump Django versions

A bugfix release for 1.7 was released which contains many migration
fixes. Also bumped the minimum 1.6 version as we were already lagging
two releases behind.
Transifex: Don't push translation

A Travis CI bot automatically extracts the source strings and pushes
them to Transifex. Previously, this bot also pushed translations, which
does not make sense, as the translations are made at Transifex.
Surprisingly, this didn't seem to cause much trouble - my best guess is
that Transifex respects modification times and ignored the pushed
translations. It certainly does so for source files.
But @mvantellingen reported that Dutch source files were overwritten. I
just did a manual push of only source files, and the Transifex UI still
shows all languages as updated. It makes sense as the source strings
changed, but makes me wonder if Michael saw actual overwrites.

Either way, pushing translations was the wrong thing to do. And as
nothing should go wrong with the English source file, I removed the skip
flag.

I intent to re-enable the bot once we've released 0.8.
Fix cursor:pointer for labels on dashboard statistics

The totals displayed on the store statistics are <label> elements, which
causes a mouse cursor suggesting they're clickable. This commit fixes
that.

@maikhoepfel rebuilt the CSS with less 1.7.5. Annoyingly, even without
this change, all the sourcemap files were updated by that. No idea why.

Closes #1526.
Merge pull request #1524 from machtfit/update-phonenumber

Update phonenumber dependency
Update less to 1.7.3 and enable source maps

Don't use requirements-less.txt now, instead just use npm to install less.
Don't overwrite bootstrap error, success and information alert colors

http://getbootstrap.com/2.3.2/components.html#alerts

git blame doesn't reveal any useful information as to why this was added in
the first place.
Use bootstrap button color instead of the same color for all button types
Leave non-wysiwyg text areas alone

as was the intention according to the comment above the CSS rule.

Without this regulating the size of the textarea with
attrs={'rows': x, 'cols': y} was not effective.
Bigger font for inputs
Remove unused CSS

There's no category-selected in the Dashboard as far as I can find
Actually use the variables from variables.less
Set a bigger font size and more readable font

The previously used font was too thin.
Visually connect tabs with tab content through a well
Don't mess with my CSS like this!
Use more down-to-earth z-index.

The effect is the same.
Remove deviations from stock bootstrap that caused problems

They came into oscar mostly in several-1000-lines commits with messages
like "dashboard improvements", so there's no way to find out why they were
added.
Reduce whitespace above black bar at the bottom and the form above
Undo border color changes that didn't catch all borders
Add CSS to vertically align plain text with the label in a horizontal form