Fix check_lib in configure script (#398)
Merge review 221 by @srh (Fix #398)
Merge branch 'next' into sam_no_program_options

Conflicts:
	configure
Merge branch 'next' into sam_no_program_options

Conflicts:
	configure
Merge branch 'sam_no_program_options' of github.com:rethinkdb/rethinkdb into sam_no_program_options
Made us not initialize pid_file with NULL.
Added exists_option, used for --help, now rethinkdb create works.
Made main_rethinkdb_serve use the new kind of options.
Made main_rethinkdb_proxy use the new kind of command line options.
Made main_rethinkdb_import use the new kind of options.
Made main_rethinkdb_porcelain use the new kind of options.
Made main_rethinkdb_porcelain not subtract 2 from argc when parsing (it should only subtract 1, because there was no subcommand).
Implemented crappy word wrap with help paging fgor rethinkdb create command.
Made help_rethinkdb_serve, help_rethinkdb_proxy, and help_rethinkdb_import use the new parsing system.
Made, uh, help options not serve the wrong options, and made us use the new system for porcelain help.
Removed old get_rethinkdb_porcelain_options function.
Added parse_command_line_ignore_unrecognized (not yet used).
Refactored parse_command_line_ignore_unrecognized to parse_command_line_and_collect_unrecognized.
Hooke up main_rethinkdb_admin to new command parsing system.
Implemented parse_config_file, which possibly works.