Todos before v0.1 testing release

[IsaacKhor]

There's a bunch of stuff we really should do before this touches any production server:

liblsvd:

• Set up a testing suite
• Build existing tests and make sure they pass
• Add an error handling path for failed IO requests (massive project)
• Refactor image open path to correctly handle errors
• Consolidate unused classes (img_reader, file_backend)
• Remove libaio dependency
• Add tcmalloc back in

imgtool:

• Fix all the cache creation and manipulation stuff
• Merge in thick-image
• Add more information to the info command

Pt1 in #23