URLFetch service depends on optional parameters.

URLFetch service uses optional<T> and optional_with_default<T> from
Cocaine Core 0.10.3. Bump build dependencies.
Proper dependencies for the URLFetch service.

The service depends on libswarm1, not libswarm.
Provide URLFetch development headers.

URLFetch service development headers for use with the Native Framework.
Slave output capture in the CGroups Isolate.

Adapt the slave output capture logic from the Process Isolate.
Merge branch 'master' into ipvs