Button selector inset and change corner radius to 2dp

Conflicts:

	library/src/main/res/drawable/md_item_selected.xml
	library/src/main/res/drawable/md_item_selected_dark.xml
	library/src/main/res/values/dimens.xml
Two separate selectors: button and normal;
Normal selector for lists and stacked buttons
Button selector for side-by-side buttons
Padding in selected item drawable replaces padding in styles

Conflicts:

	library/src/main/java/com/androirc/materialdialogs/MaterialDialog.java
	library/src/main/res/drawable-v21/md_btn_selector_ripple.xml
	library/src/main/res/drawable-v21/md_btn_selector_ripple_dark.xml
	library/src/main/res/drawable/md_item_selected.xml
	library/src/main/res/drawable/md_item_selected_dark.xml
	library/src/main/res/values-v21/styles.xml
Fix stacking algorithm;
also tweak button min-width and button frame margins for insets

Conflicts:

	library/src/main/java/com/androirc/materialdialogs/MaterialDialog.java
Woops, re-add md_selector
Update gradle build script
Delete logging
Release v0.2.4