Fix #90:[java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- replaced simple casts to instance of checks
- removed unreachable code
- removed handling for unsigned values
because in Java, all types are signed
- replaced EwsUtilities.EwsAssert(...) with Exceptions
Fix #90:[java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- imports optimized
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- Fixed Errormsg
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- added Junit Test as mentioned by @vboctor
- the testAddSupportedElementsToDictionary() shows another issue because
validation of Elements only allows Int, long, byte, boolean primitives
but casting a primitive to Object also makes it a wrapper
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- JavaDoc clarified @vboctor
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- moved assignment of UserConfigurationDictionaryObjectType.StringArray
in the StringArray block
- assignment of dictionaryObjectType, valueAsString now where it is
needed. Variables are also made final for single assignment.
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- fixed JUnit
Fix #94: [microsoft.exchange.webservices.data.ServiceLocalException] When adding Elements to UserConfigurationDictionary

Always check for wrapper types since there is no contentual difference
except of being null. which is added to the conditions.
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- null checks as independent statements. @vboctor
Pull request #90: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration

- added conversion from Byte[] -> byte[] for avoiding Exceptions as
mentioned by @Noblebrown
- added Byte[] to the Test
Merge pull request #92 from serious6/master

Fix #90 and #94: [java.lang.ClassCastException] When adding HTMLSignature to userConfiguration