repo: capitalize default prompt char

It is common in command line tools to indicate what the default answer
will be if the user simply hits enter.  In repo, the display is just
"y/n" with no indication as to which is the default.  So change the n
to N in the messages since that is how repo operates.

Change-Id: I81819ae630355072eb0365e59168b0921289498f
2 files changed