Add config for right-to-left progress (for RTL languages)

[ian-craig]

To properly support RTL languages like Hebrew, the progress should be able to animate right-to-left.

This adds an option to configure the progress bar to be RTL:

rtl

Change the progress direction to right-to-left. (default: false)

NProgress.configure({ rtl: true });

[oliviertassinari]

@rstacruz Any plan on support right-to-left? :)

[drinkmaker]

This solution works perfectly #206

[shayaulman]

@rstacruz , is there any chance that this PR will be merged soon?

This solution works perfectly #206

The issue is about adding a rtl option to the config.
(besides that editing the node modules directly is never a [perfect] solution).

[Iliyass]

this PR should be merged! @ian-craig thank you for your contribution.

[mhaneef50673]

@Iliyass Any idea when this PR will be merged?