Issue/1479

[sanredz]

This adds work towards Issue #1479

We added functionality, and accompanying tests, for four commands:

• http template It is used to create a new command template. It takes three parameters at a minimum and then after that it also accepts key/value pairs, not single params like --something

• http editt It is used to edit a template. It takes three parameter no equality signs. It does not take multiple.

• http runt Runs a command. It takes one parameter .

• http delt Deletes a template. It takes one parameter

The changes are:

• In a new file at httpie/cli/argtemplates.py
• In httpie/core.py
• In a json file httpie/cli/templates.json

We are a group of KTH students and this was for a school project. Our time ran out so we didn't have time to fully develop it. Things that would be good to add:

• Adding functionality for running a template with parameters.
• Adding better input validation.
• Adding a --help section.
• Adding single params to the template.
• Editing multiple params in a template at the same time.