The fist commit on a app who only works as a simple calc.

Signed-off-by: SamuraiCoder <sam.alonso@gmail.com>
- Added a new Activity to show the result. Pending to implement an
Intent call to work in.
Changues to implement new version in a paralell project.
New Activity created to show the result. It takes only operator1 and the
last operator2 to make an operation.
Reorganize code in ListenerAPP. Each button method called the same part
of code excepto the '0' so I decided to change.
Commit all code.