Fix date format related issues

Synchronization/instance sharing, typos
Fix more findbugs warnings
Fix more findbugs warnings
Fixes #14 : StandardComparisonStrategy was not working with list of arrays
Merge pull request #59 from ash2k/findbugs-fixes

FindBugs fixes
Merge pull request #55 from twillouer/issue17

fixes #17
Fixes #17 : add code examples in javadoc
Fixes #17 : add doesNotContainEntry assertion in MapAssert
Improve javadoc
Fixes #66 Mix in test case name and tested methods
Add Thanks section
refactoring : StandardComparisonStrategy comparator is now local to newSetUsingComparisonStrategy method
CONTRIBUTING.md minor improvement
Fixes #12 : MapAssert.containsKey should use varargs params
Fixes #12 : MapAssert.containsKey should use varargs params

Conflicts:
	src/main/java/org/assertj/core/api/MapAssert.java
Fixes #15 : isEqualTo should not use generics.
It allows to pass a parameter whose declared type is not actual's type
Fix warnings
;;