B"H net_io: http: check if file can be sent
B"H net_io.c: add missing else statement
B"H net_io.c: http serve: return HTTP response codes
B"H net_io.c: use %d like local code
B"H net_io.c: http server: content should be dynamically allocated
B"H net_io.c http server: hopefully mem code is OK now

Still learning the ropes memory-wise :-)
Merge branch 'master' of https://www.github.com/MalcolmRobb/dump1090 into http_server_wk
Merge branch 'master' of https://www.github.com/MalcolmRobb/dump1090 into http_server_wk
Merge pull request #3 from hhm0/http_server_wk

Various Http server fixes for file existence checking and error handling