added textView to display total number of repetitions
Implemented counting and display of total repetitions
Timer duration values is read from preferences
Init Exercise button shows dialog , that allows to enter timer duration. Dialog UI needs major rework.
Re implemented dialog using DialogFragment. First step to UI amelioration.
removed unused dialog implementation
renamed id of UI elements
Some dialog UI enhancements
Merge pull request #7 from MyDogTom/shared_preferences

Using preferences to store timer duration
Merge pull request #8 from MyDogTom/count_repetitions

Count repetitions