Update howler dependency version

[dmednis]

Changed the howler dependency version to allow for semver patch version changes.

[thangngoc89]

Hey thank you for send us this PR but we are well awear of the semver and opted for a fixed versiom because even though howler.js follows semver, they usually introduced bugs in patches that break our production builds.

[dmednis]

Fixed version it is then.

[thangngoc89]

Thank you. @Stenerson could you please check if this version of howler is working fine for you? And make a new release.

[Stenerson]

Yes, I'll run a few tests (hopefully today) to make sure 2.0.6 checks out and merge this.

[Stenerson]

@dmednis let's bump to 2.0.7 since it includes a minor cosmetic fix and would get us to the most current version.

I still want to run a few tests on the stuff that was changed in 2.0.6 but we can basically get to .7 for free so let's do it.

[thangngoc89]

@Stenerson I can add greenkeeper to the project for reminding you of newer version of howler.

[Stenerson]

Good idea @thangngoc89.

I knew that they had a few patch releases but didn't realize that .6 fixed a nasty deprecation warning in Chrome. They don't release too often so sticking with this plan should be manageable.

[dmednis]

Didn't notice there was a .7 released. But yes, upgrading to the latest would be great.

[Stenerson]

2.0.7 Seems to be working fine but there's still a deprecation warning.
See goldfire/howler.js#856

@dmednis can you please update to 2.0.7 and run yarn upgrade howler to update (and commit) the yarn.lock file as well? Then I'll merge. Thanks again and be on the lookout for another bump when Howler releases a version to kill the remaining deprecation warning.