Pollen.com component instead of REST sensor

[brianjking]

• Pollen.com component implemented in 0.63 release
• https://github.com/brianjking/homeassistant-config/blob/master/sensor/pollen-rest-sensor.yaml

Re: #126 & #118

[brianjking]

- platform: rest
  name: pollen
  resource: https://www.pollen.com/api/forecast/current/pollen/60640
  value_template: "{{value_json.Location.periods[1].Index}}"
  scan_interval: 21600
  headers:
    Referer: "https://www.pollen.com"

- platform: rest
  name: cold_flu
  resource: https://www.pollen.com/api/forecast/extended/cold/60640
  value_template: "{{value_json.Location.periods[0].Index}}"
  scan_interval: 21600
  headers:
    Referer: "https://www.pollen.com"      

    pollen_level:
        friendly_name: 'Pollen Level'
        value_template: >-
          {%- if states.sensor.pollen.state|float <= 2.4 %}
              Low
          {%- elif states.sensor.pollen.state|float <= 4.8 %}
              Medium-Low
          {%- elif states.sensor.pollen.state|float <= 7.2 %}
              Medium
          {%- elif states.sensor.pollen.state|float <= 9.6 %}
              Medium-High
          {%- elif states.sensor.pollen.state|float <= 12.0 %}
              High
          {% else %}
              Unknown
          {%- endif %}
    cold_flu_risk:
        friendly_name: 'Cold & Flu Risk'
        value_template: >-
          {%- if states.sensor.cold_flu.state|float <= 2.4 %}
              Low
          {%- elif states.sensor.cold_flu.state|float <= 4.8 %}
              Medium-Low
          {%- elif states.sensor.cold_flu.state|float <= 7.2 %}
              Medium
          {%- elif states.sensor.cold_flu.state|float <= 9.6 %}
              Medium-High
          {%- elif states.sensor.cold_flu.state|float <= 12.0 %}
              High
          {% else %}
              Unknown
          {%- endif %}