[SimlarService] Code Cleanup: added static to class

  * This is part of issue #91.
[SimlarCallState] CodeCleanup: auto generated toString

  * This is part of issue #91.
[ContactsProvider] moved function to load contacts from telephonebook here

  * This is part of issue #91.
[ContactsProvider] moved http request to get contact status here

  * This is part of issue #91.
[ContactsProvider] moved classes ContactData and FullContactData here

  * This is part of issue #91.
[ContactsProvider] added toString to ContactData

  * This is part of issue #91.
[MainActivity] now loads contacts itself

  * This is part of issue #91.
[SimlarStatus] removed LOADING_CONTACTS and ERROR_LOADING_CONTACTS

  * This is part of issue #91.
[ContactsProvider] now provides async contacts loading

  * This is part of issue #91.
[ContactsProvider] now provides async contact name and photoId loading

  * This is part of issue #91.
[SimlarService] now showes contact's picture in the notification if available

  * This is part of issue #91.
[ContactsProvider] is implemented as Impl now

  * This is part of issue #91.
[ContactsProvider] now caches data

  * This is part of issue #91.
[SimlarService] now pre loads contacts

  * This is part of issue #91.
[MainActivity] added menu entry for reloading contacts

  * This is part of issue #91.