v0.0.4 implement strings and ints

implemented:

• ints (except for signed Int64)
• strings (if length > 2^16, it's untested)
• benchmarking tests
• some modularization of code, mainly into encoding/decoding and msgpack format types. so code that handles encoding strings lives in modules/encoding/string.bal

Full Changelog: v0.0.3...v0.0.4