drop `entries` variable and use `map!` instead of `map` on new array to save new object creation
use `map!` instead of `map` on new array to save new object creation

also change "1.0" (string) to `1.0`(float) since we save conversion from `to_f` applied on it
Extract `DROP_BODY_RESPONSES` to a constant
avoid creating an array an then doing a join by use of string interpolation
extract `ETAG_KINDS` to a constant

also use string interpolation instead of  addition
use destructive merge operations on `options` to save new hash creations
change `.` indentation to fix jruby syntax error
Merge pull request #743 from vipulnsward/minor_optimizations

Minor optimizations