Database work for moderation

 * db/migrations directory to slightly organise our migrations
   (no instrumentation is yet provided for this.)
 * db/schema is also updated
 * added moderation user, timestamp, and comment fields for
   pledges and comment
 * added ishidden field for pledges, to match that for comment
 * updated some code to disambiguate ishidden where necessary
 * prominence calculation function honours ishidden
OPTION_MODERATE_PLEDGES redirect and creation

 * check moderation status when viewing a pledge
     - NB: we might not even need to update search.php, as pledges
       don't appear until they have signatories, and unmoderated pledges
       can't have those?
 * set pledge to hidden by default if option is set.
 * show a holding text to user (to be discussed with client)
    - NB: do we need a Next Action here instead?
Allow remote "subadmin" access

This adds several new config variables:
    OPTION_ADMIN_REMOTE_SUBADMIN - whether to enable this
    OPTION_ADMIN_LOCKED_FIELDS_SUBADMIN - locked down subadmin access fields

These all use the CGI variable REDIRECT_REMOTE_USER, as per proxied access,
or REMOTE_USER, which may be useful if not running on mySociety servers.

We also have a utility method for accessing a user object for these users,
get_admin_user.
Moderation details on moderating comment
default web-admin page to 'summary'
Moderation: Open/Closed admin => mode tabs

New $moderation_condition for searching for pledges to administer,
and refactored to mode tabs to make display more flexible.
Basic moderation of pledges

with colour
Make /my page aware of moderation
Improve breadcrumb logic through pledge creation

pass a "page" string instead of a page number, and improve the wording
of "Category / Privacy" if we're not actually supporting privacy.
Basic RBWM skin

Have copied the header and footer from RBWM Petitions, and merged
former with the Pledgebank one.
RWBM microsite settings for location/privacy
Update list of popular social networking sites

Welcome to Web 2.0, please drive carefully.
Replaces #84
remove unnecessary things, blank styles.css, stubbed breadcrumbs

removed
 - unneeded styles
 - left nav
 - related links
RBWM styling work

 - header styles - remove some purple, make it look more like RBWM
 - Remove background image
 - styled search bar
 - fix to remove weird vertical space under nav
 - pledgebank design will now use 100% of available space within rbwm template
 - tweaked layout and design to make form more prominent
 - fixes to override specificty breaking the govmetric styles
 - tweak to new pledge layout
 - normalise all the purple boxes
 - border, fix float drop
 - lots of purple!
 - Removed padding from rss links
 - correct positioning of start button
 - style front page lists of pledges
 - correct spacing a layout of pledge information
Email templates for moderation

Fixes #66

* Moderation email honours microsite of pledge

Some circumlocution, due to microsite not being set within the admin.

* Localise email site name and sender

Note that the Admin page doesn't tend to have a microsite set: you can
explicitly do this, but to avoid missing anything, in single-customer
sites (such as the RBWM case) it may be easier to use the new
OPTION_FIXED_SITE_NAME override.
RBWM: Removed "My Account" link
Styling/details of PDF posters for RBWM

This fixes #70, or rather the root reason that ticket was logged:
we don't want the flyers to refer to SMS, as we're not using that
for RBWM.  Instead of disabling the whole feature, we flesh out
the stubbed 'has_sms' function, and the PDF generation routine
already does the right thing here.

In addition, we make the Python code aware of microsites, in order
to be able to apply styling (yuck, see #98)
Timeline includes moderation (of pledges/comments)

Fixes #81
Tweaks for RBWM

 - Allow hiding of Success Stories, Fixes #93
 - Reorganise CSS for rbwm frontpage, Fixes #94
 - Login button and link to /my,  Fixes #95
 - align successful & comments on front page
    by floating the comments box RSS icon to the right.
 - Disable local alerts for RBWM
Move more edit functionality to admin_allow('techy')

 - "Edit Pledge Text" - as requested by RBWM for #91
 - delete pledge entirely (moderation better for this case!)