Fix 5.3.1 by providing find and json in one big chunk

[tannewt]

Fixes #32

@anecdata, mind reviewing this?

[anecdata]

Adafruit Feather M4 Express with samd51j19
CircuitPython 5.3.1 on 2020-07-13
CircuitPython Library Bundle 6.x-mpy-20200918 but using this adafruit_requests.py

The _find function is working to get past the AttributeError: 'bytearray' object has no attribute 'find' - (some) requests are getting sent and responses received correctly. I may be seeing the separate socket/timeout issue (Failed to send 247 bytes (sent 0)), will need to narrow down.

I can run a few basic JSON tests too.

[anecdata]

OK, simpletest with JSON GET and JSON POST both seem to work fine. Also tested a 1300+ character JSON @ http://httpbin.org/post and it went out and came back fine.

So it looks to me like the reported find issue is addressed.

I also tried HTTPS versions of the URLs in simpletest, but got:

Fetching text from https://wifitest.adafruit.com/testwifi/index.html
Traceback (most recent call last):
  File "code.py", line 54, in <module>
  File "/lib/adafruit_requests.py", line 605, in get
  File "/lib/adafruit_requests.py", line 478, in request
  File "/lib/adafruit_requests.py", line 418, in _get_socket
  File "/lib/adafruit_requests.py", line 573, in wrap_socket
AttributeError: 'NoneType' object has no attribute 'TLS_MODE'

Although I don't get that error in my own code.py with this library, not sure why there would be different behavior in simpletest.

I can do more this weekend and file separate issue(s) depending what I find, unless you have a good feel already for the failed to send / No sockets available, and TLS exceptions.

addendum... realized the legacy interface is requests.set_socket(socket, esp) and that doesn't get the TLS exception, but I get other ESP32 errors, so I'll keep working on that.

addendum 2... well, I thought for sure I've done it before, but apparently https://wifitest.adafruit.com/testwifi/index.html is not a legit TLS website, but the other URLs in simpletest are fine with HTTPS. So with the legacy interface + legit URLs, HTTPS looks fine. Down to just the failed to send / No sockets available.

[tannewt]

Approved by @anecdata