* Deadline passes but militias say their troops ready
* Assembly mandate expired earlier this month
* GNC president says army will defend its legitimacy (Repeats with no changes to text)
By Ghaith Shennib and Feras Bosalum
TRIPOLI, Feb 18 (Reuters) - Two heavily armed Libyan militias called on Tuesday on the country's parliament to hand over power immediately, in what the president of ...