Prepare for version 8.0-1.28.0

# Changes in version 8.0-1.xx.x - 2021-xx-xx

# Changes in version 8.0-1.28.0 - 2021-08-30

 * Medium changes

     - Reads bridgestrap statistics from CollecTor.

       flags present in the bridge network status continue to be

       used. Note: the presence of the running flag determines the

       value of the "running" field in details documents.

     - Allow search by overload status

 * Minor changes

     - The overload-general server descriptor should be null when

       not present and not 0

# Changes in version 8.0-1.27.0 - 2021-08-23

 * Medium changes

     - Add overload-ratelimits and overload-fd-exhausted ExtraInfo

       descriptor line fields to the bandwidth document.

     - Add overoload-general server descriptor line fields to the

     - Add overload-general server descriptor line fields to the

       details document.

* Minor changes

  <property name="implementation-title" value="Onionoo" />

  <property name="onionoo.protocol.version" value="8.0"/>

  <property name="release.version"

            value="${onionoo.protocol.version}-1.27.0-dev"/>

            value="${onionoo.protocol.version}-1.28.0"/>

  <property name="metricslibversion" value="2.19.0"/>

  <property name="jetty.version" value="-9.2.21.v20170120" />

  <property name="warfile"