I have the same issue, running the management server server and Agent on the same machine (My laptop). But cannot create custom hosts. Your solution didn't work for me. I and running a Fedora 21.
INFO: Checking for Docker version >= 1.6.0
INFO: Found Server version: 1.6.0
INFO: docker version: Client version: 1.6.0
INFO: docker version: Client API version: 1.18
INFO: docker version: Go version (client): go1.4.2
INFO: docker version: Git commit (client): 4749651
INFO: docker version: OS/Arch (client): linux/amd64
INFO: docker version: Server version: 1.6.0
INFO: docker version: Server API version: 1.18
INFO: docker version: Go version (server): go1.4.2
INFO: docker version: Git commit (server): 350a636/1.6.0
INFO: docker version: OS/Arch (server): linux/amd64
INFO: docker info: Containers: 8
INFO: docker info: Images: 126
INFO: docker info: Storage Driver: devicemapper
INFO: docker info: Pool Name: docker-253:1-3018032-pool
INFO: docker info: Pool Blocksize: 65.54 kB
INFO: docker info: Backing Filesystem: extfs
INFO: docker info: Data file: /dev/loop0
INFO: docker info: Metadata file: /dev/loop1
INFO: docker info: Data Space Used: 3.402 GB
INFO: docker info: Data Space Total: 107.4 GB
INFO: docker info: Data Space Available: 36.39 GB
INFO: docker info: Metadata Space Used: 6.619 MB
INFO: docker info: Metadata Space Total: 2.147 GB
INFO: docker info: Metadata Space Available: 2.141 GB
INFO: docker info: Udev Sync Supported: true
INFO: docker info: Data loop file: /var/lib/docker/devicemapper/devicemapper/data
INFO: docker info: Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
INFO: docker info: Library Version: 1.02.93 (2015-01-30)
INFO: docker info: Execution Driver: native-0.2
INFO: docker info: Kernel Version: 4.0.4-202.fc21.x86_64
INFO: docker info: Operating System: Fedora 21 (Twenty One)
INFO: docker info: CPUs: 8
INFO: docker info: Total Memory: 7.693 GiB
INFO: docker info: Name: localhost.localdomain
INFO: docker info: ID: WLKH:MUUW:33OQ:VCA7:F6RY:M3IP:ALWT:VT2M:445D:OU5X:HSOU:BU42
INFO: Inspecting host capabilities
INFO: System: true
INFO: Host writable: true
INFO: Token: xxxxxxxx
INFO: Running registration