`bundle update vpim` for Ruby 2.0 support
Set default development version to Ruby 2.0
Get Travis building against Ruby 2.0
Add byebug, for interactive debugging under Ruby 2
Fix quietly_try_to_purge on Ruby 2.0

The tests of quietly_try_to_purge were failing on Ruby 2.0 due to the
net-http-local gem not working with that Ruby version.  When
Net::HTTP::bind is called, it temporarily replaces the open method of
TCPSocket with a version of open that only takes two parameters. The
Ruby 1.9 version of net/http.rb calls TCPSocket.open with two
parameters, but the Ruby 2.0 version calls it with 4, and so fails with
a mismatched number of arguments error.

In fact, net-http-local doesn't seem to be necessary with Ruby 2.0,
where one can supply a :local_port argument to Net::HTTP.start, so this
commit patches lib/quiet_opener.rb to use that approach with Ruby
>= 2.0, and net-http-local on earlier versions.
Update the switch-theme.rb script allow switching to no theme
Specify a build as rbenv doesn't fuzzy match versions (Thanks to @mhl)
Slightly nicer and more robust path reference.
Add back the acts_as_xapian Rake tasks

An effect of moving the acts_as_xapian plugin out of vendor/plugins is
that its Rake tasks are no longer found.  A fix for this (although
not necessarily the best) is in this commit - load everything in
lib/acts_as_xapian/tasks/*.rake in the Rakefile.
Use Rails.root in the Rakefile

It seems more robust (or certainly easier to understand on reading
the code) to make these paths relative to the Rails root rather
than File.dirname(__FILE__).
Merge remote-tracking branch 'origin/restore-xapian-rake-tasks' into rails-3-develop
Add some instructions on removing the symlinking code.

The code in install.rb and uninstall.rb for a theme that symlinks its
public directory from the main application directory is no longer
needed.
Fix label.
Update INSTALL.md to say that Alaveteli won't run in a EC2 Micro instance

The constrained memory on Micro instances has caused two separate
bug reports on alaveteli-dev, so update the documentation to
discourage people from trying that.
Merge branch 'feature/switch-theme-none-option' into rails-3-develop

Conflicts:
	script/switch-theme.rb
Merge remote-tracking branch 'openaustralia/ruby-2' into rails-3-develop

Conflicts:
	Gemfile
Merge remote-tracking branch 'origin/feature/cleaner-attachment-image-path' into rails-3-develop
Use a better subject line than "Fake Response" for uploaded responses

The subject line wasn't being explicitly specified in
RequestMailer.fake_response and a default of "Fake Response" (somehow
based on the method name) was being used instead; this subject line
would sometimes be visible to users and authorities and caused alarm
to them.  Instead, we use the standard subject lines for followup
emails for the InfoRequest.

Fixes #1105.
Make 'rake themes:install' safer for developers

Previously, the themes:install rake task would remove the existing
theme with 'rm -rf' and re-clone the theme into place.  This is
unfortunate for a developer who has been making changes to a theme
and then runs the rails-post-deploy script, since it calls the
themes:install task which will wipe out those changes.  In
addition, when installing themes it would deliberately remove the
.git directory of the theme, so if you do want to work in that
theme you'd have to reinitialize the theme directory to be a git
repository again.

This commit changes the task so that now:

 - If a theme directory is present but it isn't a git
   repository, it's moved out of the way.

 - If there's no theme directory at the expected location after
   that step, the theme repository is cloned into place

 - The task ensures that the origin remote points to the theme's
   URL, and fetches from that remote.

 - If there are any uncommitted changes in the theme repository
   or the current commit appears not to have been pushed, the
   task exits with a helpful error.

 - The preferred branch or tag is checked out in the theme
   repository as before.

(The uninstall, install and post_install hooks are run as before.)

This shouldn't make a difference to deployed instances of Alaveteli
but will be helpful for developers who want to work on developing
a theme.

Fixes #1111.