Portuguese Translation (opentripplanner#2402)

Added the portuguese.js, pt.json, pt.mo and the datepicker for PT in
their folders. Changed the index.html and config so it uses the PT
files. Added "pt" in the makefile also.

Makefile

@@ -3,7 +3,7 @@ I18NEXT=./node_modules/.bin/i18next-conv
 LOCALE_FOLDER=./src/client/i18n
 BABEL_CFG=$(LOCALE_FOLDER)/babel.cfg
 TEMPLATE_FILE=$(LOCALE_FOLDER)/messages.pot
-LANGS=sl en fr de it ca_ES pl
+LANGS=sl en fr de it ca_ES pl pt
 JS_FILESPATH=./src/client/js/otp
 JS_FILES = $(shell find $(JS_FILESPATH)/ -name '*.js')
 LOCALE_FILES = $(shell find $(LOCALE_FOLDER)/ -name '*.po')