[FIX] L10n: Merge split phrases

RT­1931
Sentences should not be split into multiple phrases, but use l10n-inc.
[FIX] L10n: Don't nest l10n-inc on login page

RT-1931 #inreview
In the phrase 'You're connecting to the gateway A for B with limit C',
there were nested l10n-inc attributes, fix this.
The extracted phrase is now:

#: src/jade/tabs/login.jade:51
msgid "{{1:You're connecting to the gateway}}{{2}}{{3:for{{1}}}}"
      "{{4:with a limit of{{1}}}}."
Merge pull request #1572 from jublonet/feature/1931-split-translations

[FIX] L10n: Merge split phrases