History partly implemented

- resouce positional arg is optional, not necessary when doing --history
or --resources
- --history prints last sent requests. Requests are stored in
~/.restcli/config/history
- --last added but not implemented
- Wondering whether to store only body based requests or others too
since using them in --last does not make sense
Using max instead of sorting the filenames
moved getting body to another function
history impl - incomplete
history works

* --last does not need resource. Cmd args take precedence over last values
* history folder stores name of last request in 'HEAD' file
__getitem__ does not iterate

takes from file directly by calculating based on HEAD. Moved extracting
item to a seperate as part of this
history request is de-duped
handling no-history when storing
Merge branch 'history'