Allow multiple uploads

[simonrobb]

Fixes #1.

• Fix 1: When the operations JSON is unmarshalled, arrays are typed []interface{} not the expected []map[string]interface{}, so the if-branch relating to arrays on L173 is never called. The more specific typing isn't actually required so I've just updated the type assertion to operations.([]interface{}).
• Fix 2: The indexing on L174 doesn't make sense; the value of entryPaths[i] is what we want (same as L177).