Don't set jdt compiler/complience versions in Eclipse plugin

[philwebb]

The following settings don't seem like our responsibility.

org.eclipse.jdt.core.compiler.codegen.targetPlatform=1.8
org.eclipse.jdt.core.compiler.compliance=1.8
org.eclipse.jdt.core.compiler.source=1.8

[quaff]

Yes, please remove them from eclipse-code-formatter.xml, Buildship will generate rightful org.eclipse.jdt.launching.JRE_CONTAINER in .classpath.