Bug 1026059 - differentiate breadpad minidumps from memory_info dumps

this PR introduces the concept of different types of dumps.  The breakpad dumps should be handled just as they are now.  The new 'memory_info' dump ought to be detected, unzipped, and loaded into the processed crash "memory_info" key.

the "memory_info" key is also now added to the redaction list as a sensitive key.