Bug 926334 - [Gaia] To support EAP-SIM and WPA-EAP option in WLAN setting.

According to user story of Bug 926341, we have to support EAP-SIM and WPA-EAP settings option in this bug.

* Add new three pages `wifi-manageCertificate`, `wifi-selectCertificateFile`, and `wifi-enterCertificateNickname`.
* Maintain imported server certificate list.(`gCertificateList`)
* Maintain browsing files from SDCard to import certificate file.(`gSelectCertificateFiles`)
* Remove input SIM PIN option from EAP-SIM. No need to give any other option while setting WPA-EAP method = SIM/AKA.
* Given phase 2 authentication, server certificate option for setting WPA-EAP method = PEAP/TLS/TTLS
* Hack `openDialog` function to support that leave a dialog and go back to specific exit panel. 

Todo item:
* Add error dialog for error case.