Code cleanup


*.java:
Used CollectionUtils.newArrayList() as much as possible.
Made use of LDAPAttribute constructors which accepts Strings. This avoids String to ByteString conversion in client code since the constructors handle it.

AttributeBuilder.java:
Added toAttributeList() to avoid the need for client code to create a List itself.

Attributes.java:
Added several createAsList() to avoid the need for client code to create a List itself.