Resolve build warnings of deprecated String.strip/1 method

[theodowling]

I am using your library as a dependency in a personal project, and thought of committing this change to resolve some build warnings.

==> mustache
Compiling 1 file (.ex)
warning: String.strip/1 is deprecated, use String.trim/1
  lib/mustache.ex:26

warning: String.strip/1 is deprecated, use String.trim/1
  lib/mustache.ex:23

warning: String.strip/1 is deprecated, use String.trim/1
  lib/mustache.ex:58

Generated mustache app

Feel free to ignore or merge at your will.

[schultyy]

@theodowling Hey :wave:

Sorry for the long delay here, I was quite busy lately.

Thank you for the Pull Request. I've seen that the tests for Elixir 1.2 are failing right now. Can you have a look at that?

[theodowling]

Hi @schultyy

It seems like String.trim/1 isn't available in Elixir v1.2, so if there is a need to continue support for Elixir v1.2 I do understand and I'm happy if you ignore this PR :smile:.

Just don't want this to become an issue in the future as it seems like String.strip/1 will be removed completely in Elixir v2 - elixir/lib/string.ex#L827 - even thought I don't know when that is going to be released.

[schultyy]

Hmm that makes sense. I spend some time to think about this and I'd say let's move forward with this. Because this will break behavior for people with Elixir 1.2 or before, I'd say let's increase the major version and put a notice in the README about this. WDYT?

[thiamsantos]

Any news on this?

[jsmestad]

@schultyy probably OK to drop 1.2 support