* Made helper test methods static

* Refactoring to hide details of FlexboxLayout creation behind helper methods

This PR fixes the incorrect alignment where:
- justifyContent is set to either or space_between or space_around
- Views whose visibitilies are gone are included in a flex line

Also use the number of item count, which the number of gone items are filtered
where appropriate.

Fixes #162

This PR fixes the case where:
  - layout_width is set to wrap_content for the FlexboxLayout
  - End (or start) margin is set to a child
  - The child which the has the end (start) margin has the largest width in the
    same flex line (or only a single child exists)
  - The child has a positive layout_flexGrow (or layout_flexShrink) attribute set

If these conditions were met, the width of the FlexboxLayout didn't take the bottom
margin on the child into account.

Fixes #154

- AlignItems (or AlignSelf) is set to center
- Margin is set to only one side. E.g. Only right when flexDirection is column

Remove the gcloud installation part during a build is running

- flex direction is set to row (or row_reverse)
- FlexboxLayout has a TextView (or other views that expand vertically if
  not enough space is left horizontally)
- TextView's layout_width is set to 0dp, layout_height is set to wrap_content and
  layout_flexGrow is set to positive

In the situation above, the initial height of the TextView is calculated
as bigger than the actual height because at first the width is set to 0dp,
so the TextView is trying to expand vertically, but actually the height
needs to be measured again with the expanded width (by setting the
layout_flexGrow attribute)

to simplify the test code.

- Android gradle tool to 2.2.0
- Support library to 24.2.1
- Rename the androidTest apk for sending it to Cloud Test Lab
  to accomodate the latest build artifact rule

Change-Id: Id0fdf8b4168db776675ef82016fa61ae6e50280f

Remove dummy flex lines from the result of `FlexLayout#getFlexLines`.

* Add a UT to input a float value as Flex Grow.

* Parse the input value as float for Flex Grow and Flex Shrink, parse the value as int for the others.

Fix to specify list initial capacity to avoid unexpected expansion.

Copyedit README by @dbgriff 

Bump the version to 0.2.3.

Change-Id: Ieb5f9bf3d3f32faf090e91ec9015bd1dc10ba46f