* move version to parent pom
* move version properties to parent pom for easy management
* remove freemarker dependency
* delete CombinedApplicationServer
* #1871 correct spelling
* #1873 some updates for TaskQueueZkImpl
* #1875 remove unused properties in pom
* #1878
1. remove tomcat dependency
2. remove combined_logback.xml in api module
3. format pom.xml for not aligning
<description>Dolphin Scheduler is a distributed and easy-to-expand visual DAG workflow scheduling system, dedicated to solving the complex dependencies in data processing, making the scheduling system out of the box for data processing.</description>
<description>Dolphin Scheduler is a distributed and easy-to-expand visual DAG workflow scheduling system, dedicated
to solving the complex dependencies in data processing, making the scheduling system out of the box for data