Warn of installed conflicting packages before installing apps.
[sunil: Rename 'advice' to 'action']
[sunil: Action will be string constant, for better API and i18n]
[sunil: Don't show conflict warning if action is 'ignore']
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: Sunil Mohan Adapa <sunil@medhas.org>