Update translations, add Arabic, Bulgarian and Turkish.

mailbox-android/src/main/res/values-ar/strings.xml

mailbox-android/src/main/res/values-bg/strings.xml

mailbox-android/src/main/res/values-cs/strings.xml

mailbox-android/src/main/res/values-de/strings.xml

mailbox-android/src/main/res/values-it/strings.xml

mailbox-android/src/main/res/values-ja/strings.xml

mailbox-android/src/main/res/values-ro/strings.xml

mailbox-android/src/main/res/values-ru/strings.xml

mailbox-android/src/main/res/values-sk/strings.xml

mailbox-android/src/main/res/values-sq/strings.xml

mailbox-android/src/main/res/values-tr/strings.xml

mailbox-android/src/main/res/values-zh-rCN/strings.xml

mailbox-android/src/main/res/values-zh-rTW/strings.xml