Handle DownloadManager expceptions

Handles illegal state exceptions thrown by DownloadManager
on two ocassions:
* the directory sdcard/Downloads is an ordinary file
* could not create dirctory sdcard/Downloads

Change will log an error, additionally toast with information
will pop up.

Change-Id: If853d3218a188bc77c187362a70697126b90989d
Merge pull request #4 from CyanogenMod/cm-11.0

Handle DownloadManager expceptions