Added update_item REST API

DELETE and PUT actions are not implemented yet.
blist was added to requirements.txt. Gate jobs fails without it.

Related: bp rest-update-iterm

Change-Id: I440eb9a37e316db10088221d3b47ceeb1a2d0035
Fixed DELETE action in update_item method

Attribute "value" now can be omitted for DELETE action.

Change-Id: I8766e108732de4db923e084005547ace5518e274
Related: bp rest-update-iterm
Removed licence headers from empty files

According to 
http://lists.openstack.org/pipermail/openstack-dev/2013-November/020687.html 
the empty files shouldn't contain licence header

Change-Id: Ia71e7e652c0b03473dc670f7b66944f163ff811f
Merge "Added update_item REST API"
Merge "Fixed DELETE action in update_item method"
Merge "Removed licence headers from empty files"