Use config files to store whether SDMC is enabled or not

Before, it used to use whether the directory actually existed. As a result, .citra-emu/sdmc was never auto-created (something quite confusing to me until I read through the logs).
Common: Return from CreateFullPath early if the directory creation fails
Merge pull request #146 from yuriks/inttypes

Use std sized types instead of platform specific typedefs
Merge pull request #133 from archshift/sdmc-enabled

Use config files to store whether SDMC is enabled or not, auto-create SDMC dir.
Don’t fail on empty filename in OpenFileDirectly, return the archive handle instead
Merge pull request #149 from linkmauve/open-file-directly-fix

Don’t fail on empty filename in OpenFileDirectly, return the archive handle instead
Initial WIP of HLE error handling
Second revision
Rename errors.h to result.h
Changed most/all of FS to use ResultCode
Try to fix travis build
Add two remaining missing return codes in FS
Use ResultVal for returns.