This patch adds functionality to show list of remote bookmarks in hg bookmarks
command.
There is some indenting problem in the test output as the current bookmark
printing code in core can handle bookmark names of size 25 only gracefully.
The idea is taken from hgremotenames extension which has --remote and --all
flags to show remote bookmarks. However, this patch by defaults support showing
list of remote bookmarks if remotenames extension is enabled and remotebookmarks
are turned on.