Fix for timing issue in follower.Read

In the Read method, a file could be truncated or move in between when it was os.Stat'd for its maxSize and when it is actually read. This was causing errors when the file would shrink before it was read, because unexpected EOFs were occurring :D

To avoid that problem, I thought it would be safer make the reads occur on a bufio.Reader so its operating on a known amount of data in memory, rather than an unknown quantity on disk. 
So in this case I just throw away any errors because this really just ensures that the buffer is fully utilized.

Errors from reading are detected and handled where it is appropriate. If there are issues with the tail as a whole, they are caught right below by reading from `f.errc` and any issues with reading from the file would be caught and returned later when the read actually occurs. 

That was my line of thinking, thoughts?