JSON float values
Copy of titan.core#609
## Summary
JSON decoder can not decode certain float values
## Steps and/or TTCN-3 code to reproduce
Encode a float value, such as `1.23456789e-6`
## What is the current bug behavior?
`While JSON-decoding type ...: Failed to extract valid token, invalid JSON format
Can not decode type ..., because invalid or incomplete message was received`
## What is the expected correct behavior?
Decode the float value properly
## Titan version
8.2.0
## Platform details (OS type and version)
All
/cc @aknappqwt
issue