Provide variables from command line

For variables like

service {
  location "http://server/$version"
}

use -Vversion=1.0
Merge pull request #60 from stanfy/roman/variables-in-cmd

Provide variables from command line
Add checkstyle rules and adjust rules

Rules taken from https://github.com/stanfy/java-code-style
Merge pull request #61 from stanfy/roman/checkstyle

Add checkstyle rules and adjust code
Simplify how java generator can be added
Remove strong dep on Java options
Merge pull request #62 from stanfy/roman/dsl-simpler

Simpler Gradle plugin rules for adding new generator
Fix output directories
Base scrutcture for the Objective-C Source generation
Added Header / Implementation for each Helium Message
Base file generator added for Objective-C
Generation of objc-definition and implementation
Simpliest file structure implementation @interface / @implementation
Project Parser Options added (Prefix added as the first option)
Updated tests,
Updated properties visibility
Properties adde dot the class Definition
Simple tests on the project structure
objc-properties-generation
Property generation part
Types access modifiers