chore(travis): fix dropbox_key in windows build
chore(travis): fix doxygen-upload in Linux build
chore(travis): fix typo in Linux build
chore(travis): fix typo in Linux build
chore: update .gitignore
chore(travis): fix typo in Linux build (dropbox upload)
chore(travis): test doxygen-upload #1
chore(travis): restore multiple builds