Support branches and tags

[velovint]

Allow to fetch source from branch or tag where they were pushed using "ref" attribute in web hook.
Branch mask may later be configured. In our case webhook on git tag event sufficiently limits what needs to be cloned into S3.

Supersedes #22

[velovint]

@jaymccon is there a particular reason to checkout each branch into own subdir? I removed that part to reuse workspace and not clone the same code over and over again. It also makes things a bit trickier with tags when you and end in detached head, so it seems better to me.

[JuHwon]

@velovint i use seperate subfolders for every branch to create different code pipelines for each subfolder.
this feature is mandatory for me.

[velovint]

@JuHwon sorry for delay. I'll try to restore subfolder per branch functionality.

[velovint]

@JuHwon I checked changes in repository you cloned and found out that we're talking about 2 different things. I was asking about a branch specific working directory for lambda function when pulling and zipping source while you need a branch specific zip file in S3.

Your changes totally make sense to me, but I suggest to make them in separate pull request as they modify external behavior and will at least require changes to quickstart guide document.

[velovint]

@jaymccon how can I help to get this PR merged?

[EvertVerboven]

Is this going te be released soon. It seems that this is quite an important feature. No point in having a webhook listen to a specific branch while the lambda just always pulls master.

EDIT: The current behaviour should also be beter documented in the deployment guide and readme.