Added component scan mini DSL.

Hi,

I've added `ContextSupport#componentScan` methods to provide elegant way to enable component scanning in `FunctionalConfiguration`.

We can either configure scanning via named parameters...

    class ExcludingComponentScanConfig extends FunctionalConfiguration with ContextSupport {
    
      componentScan(basePackages = Seq("org.springframework.scala.context.function"),
        excludeFilters = Seq(new RegexPatternTypeFilter(Pattern.compile(".*Component"))),
        scopedProxy = ScopedProxyMode.TARGET_CLASS)
    
    }

...or via varArged list of base packages...

    class VarArgComponentScanConfig extends FunctionalConfiguration with ContextSupport             {
    
      componentScan("com.packageone", "com.packagetwo")
    
    }

What do you think? Javadoc on pull request acceptance, as usually :)

Cheers.