Can use ASC 2.0 for AIR projects; Can make AIR libraries; Framework linkage fixes

This is a bigger commit than my previous ones, but adds more stuff too :)
Main changes:   
- Pure AS AIR apps/lbraries use the ActionScript 2.0 compiler. (maybe web projects would compile too if they don't have mxml)
- It is possible now to make .swc files that have AIR code
- Pure ActionScript AIR projects don't need the Flex framework as dependency
- The framework linkage logic was quite buggy for non-Flex projects, now it should work well

I'm making some comments in the code to make it more clear.

You can add the AIR SDK + Compiler dependency quite easily:   

     ivy {
            name 'Adobe Air SDK'
            artifactPattern Os.isFamily(Os.FAMILY_WINDOWS) ?
                'http://airdownload.adobe.com/air/win/download/[revision]/[module]_Compiler.[ext]' :
                'http://airdownload.adobe.com/air/mac/download/[revision]/[module]_Compiler.[ext]'
        }
    }
    dependencies {
        airSDK group: 'com.adobe', name: 'AIRSDK', version: '15.0', ext: Os.isFamily(Os.FAMILY_WINDOWS) ? 'zip' : 'tbz2'
    ...

This parameter makes it possible that pure AS projects can specify playerGlobal.swc/airGlobal.swc in their build script. If I would not introduce this parameter, then CommandLineInstruction.groovy would add these automatically, making it impossible for users to override.    

Flex users dont need to use this since their playerglobal is added from flex-config, and that can be overidden by adding a dependency.    
Also if would be very trickly to make this flag work for Flex too, since we would need to modify flex-config or not load it at all.