avoid to format code in javadoc as it creates too much space before and after the code
Fixes #264 : Skip unexpected elements when there are none

This applies to the following methods :
- containsOnly
- containsOnlyKeys
- containsExactly
Use 2 spaces instead of one in error message when displaying a value on a new line.
Remove isEmpty in BasicErrorMessageFactory in favor or Iterables#isNullOrEmpty.
Reformat error messages to be more readable.
Use assertj assertions instead of JUnit#assertEquals
isEqualToIgnoringGivenFields now verifies that the fields to ignore exist on the type of objects to compare

Fixes #278
Add missing Deprecated annotation
Fix generics warning
Fixes #246 : allow to use private fields for field by field comparison, make this the default behavior (breaking change).
Merge remote-tracking branch 'origin/master' into java-8

Conflicts:
	src/main/java/org/assertj/core/error/ShouldContainOnly.java
	src/main/java/org/assertj/core/error/ShouldContainOnlyKeys.java