Deprecate support for Ruby 1.8.7

[crowbot]

This will require (at least):

• Plan upgrade strategy for our hosts
• Move our own hosts to ruby 1.9 (depends on After upgrade from 1.8.7 to 1.9.3, some YAML data treated as binary #2411, Make the namespace for memcached dependent on ruby version. #2410, absolute paths to images in converted PDF files #2417 and Multibyte cached attachment text can be truncated in mid-byte #2418) - still need to move nicaragua, czech republic.
• Propose recommended upgrade paths for re-users on 1.8
• Announce deprecation
• Remove crufty ruby 1.8 code
• Set 1.9 as the default vagrant ruby
• Remove 1.8 from package lists - requires Remove squeeze from supported OS list  #2582

[crowbot]

We should announce the deprecation in #2049

[garethrees]

Wonder if Travelling Ruby will be any use here.

[crowbot]

Sent out RFC on deprecating 1.8.7 https://groups.google.com/forum/#!topic/alaveteli-dev/AQ77FNN0JIU

[crowbot]

I had a quick look at Travelling Ruby - one issue is "Traveling Ruby only supports a number of popular native extension gems, and only in some specific versions. You cannot use just any native extension gem."

[garethrees]

Need to set 1.9 as the default ruby on the vagrant vms

[garethrees]

remove 1.8 from package lists https://github.com/mysociety/alaveteli/blob/develop/config/packages.debian-squeeze

[dracos]

This will fix #2683 according to the comment in

alaveteli/app/models/info_request.rb

Lines 39 to 40 in f2c538c

	# TODO: When we no longer support Ruby 1.8, this can be done with /[[:alpha:]]/
	validates_format_of :title, :with => /[ёЁа-яА-Яa-zA-Zà-üÀ-Ü]/iu,

[garethrees]

# Ubuntu
update-alternatives --set ruby /usr/bin/ruby1.9.1

[garethrees]

Looks like you need to update-alternatives for gem, but not the other other ruby-related binaries (e.g. irb, ri, rdoc, etc)

[garethrees]

Don't merge after review – wait until major release