#16923: Implement factory method in CallList to create new calls

src/com/savoirfairelinux/sflphone/client/CallActivity.java

...com/savoirfairelinux/sflphone/client/CallElementList.java

...savoirfairelinux/sflphone/client/ContactListFragment.java

src/com/savoirfairelinux/sflphone/client/SFLPhoneHome.java

src/com/savoirfairelinux/sflphone/client/SipCall.java

...avoirfairelinux/sflphone/service/CallManagerCallBack.java

...elinux/sflphone/service/ConfigurationManagerCallback.java

src/com/savoirfairelinux/sflphone/service/SipService.java

src/com/savoirfairelinux/sflphone/utils/CallList.java