Changed all Cipher and Signature method variables to object variables
Fixed Javadoc
Changed all non-private CryptoUtils methods to synchronized
CryptoUtils now throws RuntimeExceptions for fatal initialization errors
Refactored exception handling in CryptoUtils.
Exceptions which are the result of invalid input values are now thrown
Changed Mac method variable to object variable
Merge pull request #161 from L-Henke/cryptoUtilsRefactor

CryptoUtils refactorization
implemented new method getPublicFingerprint() and getKeyIdentifier() in class Identity
Class Contact:
* new field contactOwnerKeyId
* new constructor with parameter contactOwnerKeyId
* new setter and getter for contactOwnerKeyId
* new setter for contactOwner
new class ContactTypeAdapter
added test for Contact de-/serialization
in class SyncedSettings:
* added new field contacts
* added getter and setter for field contacts
* added new field initialization in class constructor
in class Identities:
* changed collection type from Set to Map in order to enable retrieving identity by key identifier
* adapted change of collection type in add() method
* added getter getIdentityByKeyIdentifier()
in Class ContactsTypeAdapter:
* use now proper ContactTypeAdapter in write() and read() methods
new class SyncedSettingsTypeAdapter
In class ConfigSerializationTest:
* split tests for SyncedSettings and LocalSettings
* changed test for SyncedSettings to use new SyncedSettingsTypeAdapter
in class Identity:
* added annotation SerializedName("keys") to field primaryKeyPair