Cannot GET /homeassistant//services

[frenck]

Describe the bug

Solving issue #49 introduced a new issue, see screenshot above.

Caused by the following lines:

node-red-contrib-home-assistant-websocket/nodes/call-service/call-service.html

Line 87 in f43287c

$.get(`homeassistant/${node.server}/entities`)

node-red-contrib-home-assistant-websocket/nodes/call-service/call-service.html

Line 101 in f43287c

return $.get(`homeassistant/${node.server}/services`)

When there is no specific server node, the extra slash makes it an invalid URL for Hass.io.
The extra slash should only be included in case node.server actually has a value.

To Reproduce
Steps to reproduce the behavior:

1. Add call service node

Expected behavior
Working stuff ;)

Screenshots
See opening post.

Example Flow
N/A

Environment (please complete the following information):

• Node Red Version: 0.19.5
• NR Home Assistant Plugin Version: 0.4.1
• Is Node Red running in Docker: yes (Hass.io)

Other (please complete the following information):

• Have you searched previous issues for duplicates?: Yes, see references.
• Did you attempt to reproduce the issue in the dev docker environment, if so what were results (See README.md): Yes.

Additional context
N/A.