Update paths with support for Library and Temp

[brandonscript]

Currently it appears that you have to specify the local path manually; this is bad practice, and we should be adhering to Apple's documents directory guidelines.

[brandonscript]

Both docs and cache are supported, let's add temp:// and library://.

static NSString* const kIXDocsPrefix = @"docs://";
static NSString* const kIXCachePrefix = @"cache://";