Support for larger input.

The read() routine for STDIN in tool/hpclient.c was missing support for files larger than 32K. Previous routine made reads of 32K max, and sent single hpfeeds of the read data. That was wrong. The correct code is to continuously read from stdint, until eof. Then send the whole buffer. Same problem applied to the socket read(). Large message support is necessary to support cuckoo, that sends a report of about 119K. The pull request fixes also bug https://github.com/rep/hpfeeds/issues/17.