Add Phus Lu's original readme text from https://github.com/phusl/machine

Signed-off-by: Robert Breker <robert.breker@citrix.com>

README.md

@@ -2,3 +2,39 @@
 
 # docker-machine-driver-xenserver
 XenServer driver for Docker Machine
+
+Creates machines on a [XenServer](http://xenserver.org/) Virtual Infrastructure. Requires a working XenServer installation. The XenServer driver depends on [`go-xenserver-client`](https://github.com/xenserver/go-xenserver-client) (must be in path).
+
+Options:
+
+ - `--xenserver-vcpu-count`: vCPU number for docker VM.
+ - `--xenserver-memory-size`: Size of memory for Docker VM (in MB).
+ - `--xenserver-boot2docker-url`: URL for boot2docker ISO image.
+ - `--xenserver-server`: XenServer hostname/IP for docker VM.
+ - `--xenserver-disk-size`: Size of disk for Docker VM (in MB).
+ - `--xenserver-username`: **required** XenServer Username.
+ - `--xenserver-password`: **required** XenServer Password.
+ - `--xenserver-network-label`: Network label where the docker VM will be attached
+ - `--xenserver-sr-label`: SR label where the docker VM will be attached.
+ - `--xenserver-host-label`: Host label where the docker VM will be run.
+ - `--xenserver-upload-timeout`: Timeout uploading VDI.
+ - `--xenserver-wait-timeout`: Timeout wating for VM start.
+
+The XenServer driver uses the latest boot2docker image.
+
+Environment variables and default values:
+
+| CLI option                        | Environment variable        | Default                      |
+|-----------------------------------|-----------------------------|------------------------------|
+| `--xenserver-vcpu-count`          | `XENSERVER_VCPU_COUNT`      | `1`                          |
+| `--xenserver-memory-size`         | `XENSERVER_MEMORY_SIZE`     | `2048`                       |
+| `--xenserver-disk-size`           | `XENSERVER_DISK_SIZE`       | `5120`                       |
+| `--xenserver-boot2docker-url`     | `XENSERVER_BOOT2DOCKER_URL` | *boot2docker URL*            |
+| `--xenserver-server`              | `XENSERVER_SERVER`          | -                            |
+| `--xenserver-host-label`          | `XENSERVER_HOST_LABEL`      | -                            |
+| **`--xenserver-username`**        | `XENSERVER_USERNAME`        | -                            |
+| **`--xenserver-password`**        | `XENSERVER_PASSWORD`        | -                            |
+| `--xenserver-network-label`       | `XENSERVER_NETWORK_LABEL`   | -                            |
+| `--xenserver-sr-label`            | `XENSERVER_SR_LABEL`        | -                            |
+| `--xenserver-upload-timeout`      | `XENSERVER_UPLOAD_TIMEOUT`  | `300`                        |
+| `--xenserver-wait-timeout`        | `XENSERVER_WAIT_TIMEOUT`    | `1800`                       |