Update English translation files.
Merge pull request #1255 from normanjaeckel/TranslationEnglisch

Update English translation files.
Updated packages in requirements_production.txt and prepare_portable.py

Added new license files of packages for portable version.
Fixed #1240 (No assignment poll form fields for votes invalid and votes cast)
Fixed #1102 (New config option to set percent base for polls)

Use locale format for poll percentage decimal number.
Merge pull request #1256 from emanuelschuetze/portable

Updated required packages and portable
Use right projector logo (as in stable/1.5.x branch).
Merge pull request #1248 from emanuelschuetze/fix-1102

New poll config option for 100% base (fixed #1102 and #1240)
Merge pull request #1257 from emanuelschuetze/projector-logo

Use right projector logo (as in stable/1.5.x branch).
Updated English language files.
Merge pull request #1259 from normanjaeckel/Translation

Updated English language files.
Added multiselection views.
Coding style changes. Small template changes.