Bug 14707 : Replace UsageStatsCountry syspref from free text to a dropdown list.

Bug 14707 : Replace UsageStatsCountry syspref from free text to a dropdown list.

This will avoid syntax problems with Hea when a user will fill this 2 sysprefs

The default choice for UsageStatsLibraryType and UsageStatsCountry is 'empty'

Test Plan
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1. Create a new Koha install
2. Go to the 'Administration' page
3. Go to 'Global system preferences'
4. Go to 'Administration'
5. At the end of this page you should see a dropdown menu for
- UsageStatsCountry with all countries
- UsageStatsLibraryType with all type of library
They both should be empty by default.

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Not a complete list but is a start
Lots of new strings to translate :)
No errors

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>