feat: Relates to #402. Internationalisation. German Language Support (#464)

* chore: Update to latest React 16.8.3 to requirements of react-i18next

* feat: Scaffold basic translation with English and German

* feat: Relates to #402. German translation fully working

* fix: Switch back to English by default

* fix: Allow user to switch between languages in preferences of context menu

* feat: Translate the context menus

* refactor: Remove German language. Add as separate PR

* refactor: Remove blank line

* feat: Add German language using Google Translate only

* fix: Fix Fether menu German language translation after review from @Robbepop (native German speaker)

* docs: Update Readme with Internationalisation Add New language instructions

* docs: Update Readme with Known Issues and Usage instructions

* review-fix: Disabled tooltip Please fill out this field. Add High and Low tx speed

* review-fix: Update license headers to be 2019 instead of 2018

* review-fix: Change ns1 to fether-electron and fether-react. Use pino.debug

* fix: Add missing i18n conversion for macOS Edit menu

* review-fix: Remove unused i18next browser languagedetector dependency

* merge latest from master and fix conflicts

* merge latest master and fix conflicts. TODO do not expose remote

* fix: Do not expose remote. Only expose add and remove listener, and reload via bridge

* feat: Convert new release available text to i18n