Fix httpGET/httpPOST line endings, Fixed httpGET to return buffer

Fixing httpGET and httpPost to have the correct line endings:
* replace LF with CRLF in the HTTP request being sent

Fixing SIMCOM900::read() to allow httpGET to return a buffer with results
* added wait to allow time for the data to be received.
* added "while available" loop to read function to read only while available

This will have to be addressed again in the future to allow continued reading after the buffer is full.