Fix possible repeated SuppressWarning with @EView

In case of @EViews, we add a @SuppressWarnings annotation to the class.
Since we also copy annotations from the annotated class, this can result
in repeated annotations. This commit fixes the issue by only adding the
annotation (or an annotation array member) if needed.
Merge pull request #1267 from WonderCsabo/1262_viewHolderRepeatsSuppressWarnings

Fix possible repeated SuppressWarning with @EView
Convert code to Java 7

Switched the processor and the API project to use 1.7 Java level. Code
has been converted to utilize the new language features.
The functional test project is still at 1.6 because we use API 19 >
which cannot use Java 7. Newer Android deps are not on Central due to
known reasons.