Allow a custom method name prefix

This contribution allows to provide a custom method name prefix instead of "with"

IMHO "with" is obsolete, as it is clear when using a builder. Also it is too much redundancy.

How to set a custom prefix or remove it.

There are two ways.

1. Create and add a pojobuilder.properties file to your classpath. 
The property file should contains the key net.karneim.pojobuilder.methodnameprefix=xx 
2. Annotation Processor Arguments (-A parameter)
http://docs.oracle.com/javase/7/docs/technotes/guides/apt/GettingStarted.html
add argument -Anet.karneim.pojobuilder.methodnameprefix=xx to annotation processor.

Maven Example:
```
         <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
               <compilerArgument>-Anet.karneim.pojobuilder.methodnameprefix=zzz</compilerArgument>
               <!-- alternative for no prefix -->
               <compilerArgument>-Anet.karneim.pojobuilder.methodnameprefix</compilerArgument>
            </configuration>
         </plugin>
```
 Depending on the eclipse and m2e annotation processor setup this setting will be also used by eclipse.