Few issues in DT plugin API: enableJavaFX

1. for the IE case, we didn't extract the input VARIANT into bool correctly.
so right now, to use the API, IE needs to do enableJavaFX(1); while FF is enableJavaFX(true)

2. HKEY_LOCAL_MACHINE\SOFTWARE\Oracle\JavaFX, value name Disabled. it's set by RegisterDeploy, and it's set even if it's a JRE install also. We should set this key only when installing JavaFX runtime.

3. when enableJavaFX is called using DT, it tries to set it while running in mediurm integrity on win7/vista. this cause the key write re-directed to : HKEY_CURRENT_USER\Software\Classes\VirtualStore\MACHINE\SOFTWARE\Oracle\JavaFX . we need to investigate and see if this is really what we want, and also if any cleanup on this key is needed.

4. Need to check if the Disabled key should have any effect on subseqent JavaFX runtime installations, either triggered by manual install or auto install.