Explicitly paginate just help text instead of all output

Before we tried to automatically paginate all `puts` output depending on
whether it fits on one page using LESS options. This didn't work as
intended, so now explicitly opt in for pagination for `hub help -p` and
`hub help hub` output.

Doing so enables us to clear the screen reliably upon exiting the pager
without risking single-page output being swallowed.

This reverts commit 45003e19524dafa7dbfe23685eb0e7010b223957.

Fixes #368
Don't allow man page width to exceed 120 characters

Text wider that that is hard to read. Also, on terminals narrower than
120 chars, provide a 1-character right margin to improve readability in
case of vertical splits.
Show `hub <command> -h` short usage help on stdout

Instead of stderr, show this help on stdout because we suppose that the
user intended to retrieve help intentionally.
Merge branch 'terminal-tweaks'
Fix `hub browse` on detached HEAD

Fixes #588
GitHub stopped supporting escaping slashes in compare URLs

When a fix for #466 landed, it was necessary to escape slashes in branch
names with `;` because they weren't supported as a path component in
compare URLs. Now slashes are supported, but GitHub stopped supporting
semicolons as means of escaping.
Add test that project wiki can be cloned
Fix `hub am` for Enterprise URLs

Still won't work for Enterprise gists, but this makes it work for pull
request & commit URLs.

Fixes #584
Bump Aruba & rspec-expectations

Also get rid of deprecation warnings for `should` and `failure_message_for_should`
Merge branch 'update-rspec'
hub 1.12.2
Merge remote-tracking branch 'origin/master' into merge_master

Conflicts:
	Gemfile.lock
	features/browse.feature