Prevent ask_password from stripping whitespace (Take 2)

Get HighLine.ask() to process whitespace with :chomp rather than
:strip (default) so that leading/trailing whitespace in user-entered
password is preserved.

It was previous fixed in lib/rhc-common.rb (now obsolete)
in commit a4dd33f717877a2d1731e9c48f1a2abac4234a30 (2012-11-30),
and appeared since rhc-1.2.3-1.  However, due to a code
restructuring which began a day before (starting with
commit 0422025c9c4ab487a7b256dfcb8f97eeaf0f7cab, 2012-11-29),
the fix was not carried over to lib/rhc/auth.rb (and later
lib/rhc/auth/basic.rb), hence this new patch.