Improve redirects when country code is not set in user languages

[pascalmoser]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	no
RFC?	no

I18n is ignoring a user locale without country code (de), when the same locale ist set in Pimcore with country code (de_CH).

Example 1:

User locales: de_CH, en
Pimcore locales: de, en

Current and expected Behavior: i18n redirects to de (working with PR #63)

Example 2:

User locales: de, en
Pimcore locales: de_CH, en

Current behavior: i18n redirects to en (ignoring de_CH)
Expected behavior: Redirect to de_CH because user preferred language should have more priority.

[solverat]

Fixed with #68.