Add to fixtures a public body with an accented initial letter

This adds a public body called "Åčçèñtéd Authority" in the
Czech locale (cs) so that we can create tests that exercise,
for example, searching based on an initial letter that has a
multi-byte representation in UTF-8.

An old test for "add mass tags" in the admin needed to be updated
since it implicitly assumed that all the public bodies in the
fixtures had translations in the :en locale.

The tests for loading CSV files of public bodies also needed to
be updated, since they were assuming that public body names
only contained letters in [A-Za-z ].  Since Unicode character
classes aren't easily available in Ruby 1.8 and it makes little
difference to the test, the character class is replaced by '.'.
Allow public body listing based on first letter outside US-ASCII

Under Ruby 1.8, it was previously impossible to use one of the "first
letter" alphabet links on the public body listing page if the first
letter was outside [A-Za-z] since the test for the parameter only
being a single letter wasn't aware of the possibly of multi-byte
characters.  In addition, upcasing of letters outside [A-Za-z] didn't
work because String#upcase in Ruby 1.8 isn't Unicode-aware.
This commit fixes these two problems, so that non-US-ASCII first
letter links will work under Ruby 1.8.

(Fixes #1112.)
Fix upcasing of a non-US-ASCII first letter under Ruby 1.8

In the rare circumstance that someone created a public body
whose name started with a lower case letter outside [a-z]
with Alaveteli running under Ruby 1.8, the letter would not be
upcased correctly before saving to the first_letter column.
This commit fixes that by using a Unicode-aware upcase function.
Merge remote-tracking branch 'origin/first-letter-unicode-fixes' into rails-3-develop