Increase LINE_BUF_SIZE to handle longest possible command

This fix addresses https://github.com/kr/beanstalkd/issues/211 and https://github.com/kr/beanstalkd/issues/212. Though issues still remain around the use of pause-tube with long tube names and large integers.

I tried the approach I suggested in the issue of changing prot.c:343 to use ```>``` instead of ```>=```, but trying to use a tube with a name of length 200 continued having issues.

So this instead updates LINE_BUF_SIZE to handle the longest possible command and reply lines.

This may be a preferable approach since both LINE_BUF_SIZE and MAX_TUBE_NAME_LEN follow similar logic in that they both represent the minimum invalid length.

Existing ct tests all pass. Additionally a suite of ~200 integration tests I wrote to test adherence to the beanstalk protocol show no regressions. Those tests can be found here: https://github.com/tdg5/beanstalk_integration_tests. They're written in ruby though, sorry :)

Any thoughts on what to do for pause-tube which could take a tube name of length 200 and could also take a very large integer which would mean making LINE_BUF_SIZE at least double its current length.