Add dropbox login persistence and class outlines for core 1Password types
WIP - Encryption key decryption
Implement main key decryption using node.js crypto lib

Using CryptoJS was producing incorrect results, for reasons
still to be determined.
Use a cleaner method to trim trailing space from master password
Type annotation improvements in onepass.ts
Build with tsc's --noImplicitAny option

This caught a bug in FileVFS.read() and clarifies the return
types of the VFS interface.
Add an interface to wrap crypto functionality

Add CryptoImpl interface for required crypto functions
add move existing Node.js-crypto based implementations
into NodeCrypto class.

This is in preparation for introducing alternative implementations
for use in other browsers in future.