Remove RubyString#chars
Add more tests
Merge branch 'develop' into java8

Conflicts:
	src/main/java/net/sf/rubycollect4j/RubyArray.java
	src/main/java/net/sf/rubycollect4j/RubyEnumerable.java
	src/main/java/net/sf/rubycollect4j/RubyString.java
	src/test/java/net/sf/rubycollect4j/RubyStringTest.java