Fixes #22 - Copy of InputStream* asserts and tests adjusted for Reader
Merge remote-tracking branch 'origin/feature/issue22-readerassert' into feature/issue22-readerassert

Conflicts:
	src/main/java/org/assertj/core/api/AbstractReaderAssert.java
	src/main/java/org/assertj/core/api/ReaderAssert.java
	src/main/java/org/assertj/core/error/ShouldHaveEqualContent.java
	src/main/java/org/assertj/core/internal/Diff.java
	src/main/java/org/assertj/core/internal/Readers.java
	src/main/java/org/assertj/core/internal/ReadersException.java
	src/test/java/org/assertj/core/api/Assertions_assertThat_with_Reader_Test.java
	src/test/java/org/assertj/core/api/ReaderAssertBaseTest.java
	src/test/java/org/assertj/core/api/reader/ReaderAssert_hasContentEqualTo_Test.java
	src/test/java/org/assertj/core/internal/ReadersBaseTest.java
	src/test/java/org/assertj/core/internal/readers/Diff_diff_Reader_Test.java
	src/test/java/org/assertj/core/internal/readers/Readers_assertEqualContent_Test.java