Add RequestsManager interface

Add RequestsManager interface

RequestsManager interface defines API for taking actions
triggered by matcher events on requests structures.

The mock implementation of interface is provided in matcher package.
It is generated using mockgen command:

mockgen	-package matcher \
	-destination=matcher/requestsmanager_mock_test.go \
	-write_package_comment=false \
	git.tizen.org/tools/boruta/matcher RequestsManager

Change-Id: Idbf83988dba4cfa761dbfe8cae0a33d0a39245ac
Signed-off-by: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>