Consider the number 0 a non-empty value even though it's falsy. [Fixes #2533040]
Update precompiled template sample.
Fallback to default attribute values when invalid values are used.

When an `ATTRS` setter returns `Y.Attribute.INVALID_VALUE` during
initialization, and a default attribute value is defined, fallback to
that value.

Fixes #2528732
Add more tests for Attribute default value fallback.
Template.Micro: Fix improper escaping of control chars.
Updated Gallery Build Stamp
Using yogi loader to build meta-data
Removing shifter and using yogi to build
Seed and Loader Build
Build template-micro.
Merge branch 'dev-master' into bug-template-zero
Dropping the git level to 30
Bumped up request dependency
Merge branch 'attr-init-val' into dev-master

Conflicts:
	src/attribute/HISTORY.md
Build Attribute.