Merge branch 'jk/git-prompt'

* jk/git-prompt: contrib: add credential helper for OS X Keychain Makefile: OS X has /dev/tty Makefile: linux has /dev/tty credential: use git_prompt instead of git_getpass prompt: use git_terminal_prompt add generic terminal prompt function refactor git_getpass into generic prompt function move git_getpass to its own source file imap-send: don't check return value of git_getpass imap-send: avoid buffer overflow Conflicts: Makefile