modify the 'Add' buttton in the CreateExpense

- Create separate layouts for EditExpenseActivity and
  CreateExpenseActivity.
- Implement an addExpense button design at the bottom of the
  CreateExpenseActivity.
Implement new design for the CreateExpenseActivity

- Center all of the editTexts in the middle of the page.
- Implement the needed drawables and selectors so that the views respond
  to clicks.
show months as a word in the dateView
add all SD layouts for CreateExpenseActivity
Implement buttons design in EditTextActivity

- attach icons to the buttons
- put them at the bottom of the activity
- impelement a left separator in edit button
Apply the same layout to showExpenseActivity

Decided in order to avoid confusing the user with different layout is
edit/show/create Expense Activities to implement the same layout for all
of them.

- apply layout of CreateExpenseActivitiy to ShowExpenseActivity
Apply formatting to ShowExpenseActivity

- Show the month as a word
- Format the amount and apply the currency
Optimize the layouts for all screen densities

- Provide the layouts for all screen densities.
- Make all of the button texts CAPS.
change labels in the manifest
show the full date in EditExpenseActivity