[bluez] Delay dial after hold. Fixes JB#11613.

As we're not getting ofono result codes, have to delay dialing
after primary call is put on hold; otherwise ofono may fail
the dial attempt with "InProgress" code.
Merge pull request #25 from hmallat/telephony-hold-and-dial-v2

[bluez] Delay dial after hold. Fixes JB#11613.