Numerous small fixes

  - Updated configure script to catch missing libcurl.
  - Fixed src/Makefile to have bucket.c in correct source list.
  - Remove unused function decl from library.h.
  - Removed explicit inlining of functions in bucket.h.
  - Fixed comment in library.c.

Signed-off-by: Alex Waterman <alexw@imNotListening@gmail.com>