Cleaner code

- Removed two unused variables in PlotMe.java
- Merged 'else if' statements in PMCommand.java
- Removed unnecessary code from PMCommand.java
- Updated dependencies in pom.xml
- Added text to README.md
- Removed .idea files because not everyone uses IntelliJ. These files should not be in the GitHub Repository. 

Additions will be added below as committed. 
Bukkit is provided