readme updates to reflect v3 support
R16B no longer requires patched SSL for NPN
header parsing validation in v2
Parse multiple header values into a list (v2)
Validate header names (v2)
validate header names/values in v3
Don't allow duplicate header names
Propagate header validation errors outside parser

These will be a tuple of the form:

```
{error, stream_protocol_error, [{streamid, 432}, {frametype,
?SYN_REPLY}]}
```
don't crash when NPN fails
Merge pull request #5 from bgentry/header-validation

Header validation, split multi-value headers into a list
oops, 0-length header values are *allowed* in spdy/3
Merge pull request #6 from bgentry/v3-allow-empty-header-values

0-length header values are *allowed* in spdy/3