Performance improvements for the mobile app

We should improve the performance, specially in the pre-fetch areas, suggested improvements are:

• Sections download must be disabled: We should add a new icon on top of the sections page (the cloud icon) to enable downloading. When the user clicks in the icon, the download status for all the sections start being calculated)
• isDownloadable: In every module implementing it, it should use aggressive cache when possible.
• getModuleStatus: Should use aggressive cache too