switched from blockblobs to pageblobs

also fixes bugs introduced by a misunderstanding of UploadFrom methods (they rewrite the blob, and don't append)
bit of refactoring/renaming + added a blob for additionnal stream info

the second blob is a block blob and is intended to store additional indexing data to be retrieved when the program restarts
LocalCache is now EventIndexer (i have some problems choosing names)
still no tests
merge