Applied non-button dismiss fix to Confirm Dialog

[Fix][Mod]: Confirm Dialog now sends a negative button press whenever
cancelled. Additionally, on click interface now dismisses automatically.
Moved listview, added padding to listview, fixed colouring issue

[Ref]: Moved the listview into its own file for easier maintaince
[Fix][Mod]: Added vertical padding to bottom of listview & fixed
flashing listview issue in 2.3.3
Added checkbox drawables & set secondary text colour

[Add]: Added the drawables for the checkbox and set it in theme/styles.
[Fix]: Set the secondary text colour to be grey, primary to be black.

This closes issue #6
Adjusted the horizontal padding for xlarge, w700dp, w820dp

[Add][Mod]: Reduced the horizontal padding for 820dp and added it for
xlarge/700dp
[Mod]: Changed method of setting pref defaults

Taken from the project CareerStack, its an easier way to maintain
preference defaults
[Mod]: Added explicit support for large screens

This is required for pre-API 13
Simplified DateFormatter & removed plurals

[Mod][Dep]: Simplified the DateFormatter by moving to DateUtils;
previously it was a nice experiment to see how to create a relative time
display. However, to tidy it up moved to use DateUtils. As such
deprecated old methods.
[Mod]: Removed deprecated methods from mainfragment

[Rem]: Removed the now unused plurals from strings.xml
[Fix]: Integers are set separately to other preferences

The attempted shift to an xml based preference system hit a snag:
EditPreference, ListPreference, Preference, etc. None of these will
store in a manner than can be retrieved by getInt(String, int). This is
quite bothersome.

So, in meantime, falling back to old methods until extending the
PreferenceClasses.
Merge branch 'feature.preftweak'
[Fix]: Added safety to MainFragment to activity was not null

In the method, updateSourceCurrency() a null check is performed on the
activity to prevent potential null errors. 

[Mod][Rea]: Additionally turned off debugging to remove Log "noise".
[Mod]: Updated versionCode/name for next release

Version 3.1:
- Updated settings/preference screen graphics + text colors
- Update date formating
- Tweaked feature handling

Additionally, added android:anyDensity="true" to supported screens.
[Doc]: Updated screenshots for project's README