added compression methods option for passing to jpeg-compress

[ramiroaraujo]

I added the option to select the compression method, with the same ssim default. Didn't want to introduce many changes, so I opted for the Array type option and grabbed the first one, since there wasn't a String option and didn't want to map the methods with numbers

Let me know!

[toy]

I've already checked and String and Symbol don't work for options and I need to fix this. But your changes don't work too, so, unless you would like to make String and Symbol options work, this will have to wait.

[ramiroaraujo]

woops, let me check :)

[ramiroaraujo]

Ok, I added only String to options, and it's working fine and all tests pass. Let me know if anything, and sorry for the rushed PL yesterday, I didn't even check the contributing text :(

[toy]

Much better! Two more things: you don't check the input and as there are only certain allowed values it would be better to limit to them and (following how it is done for other workers) warn about wrong value and use the default; and as the names are not really obvious it would be better to add explanation like in documentation for the project to the values in description.

[ramiroaraujo]

done!

[toy]

Hi Ramiro,
I am sorry for long wait, are you still willing to finish with this PR?

[toy]

Space before [ and @ramiroaraujo are missing

[ramiroaraujo]

Hi, long time no see! I'll try to catch up on this probably this weekend