chore(CHANGELOG): Fix title style [skip ci]
chore(CHANGELOG): Fix v2.0.1 title [skip ci]
docs(README): Add Alternatives section [skip ci]

Add an Alternative section containing other tags-input components one may
want to check out.
chore(README): Add waffle.io badge
fix(tagsInput): Fix display of non-string items

Fix getDisplayText() function in both tagsInput and autoComplete
directives so that non-string items are correctly displayed.

Closes #150
chore(build): Update build files [skip ci]
chore(README): Update waffle.io badge [skip ci]
fix(tagsInput): Remove dependency on interpolation symbols

When the interpolation symbols are changed from the default ones
({{ and }}) the tagsInput directive's template is rendered invalid
since it's using the default interpolation symbols. To fix that, replace
that dependency with a new helper directive, tiBindAttrs, which binds
attributes to properties of the scope and keep those attributes always
up-to-date.

Closes #151
chore(build): Update build files [skip ci]
fix(tagsInput): Replace interpolation with ngBind

Replace the interpolation markup in tagsInput directive's template
with the ngBind directive.

Relates to #151
chore(build): Update build files [skip ci]
chore(release): Bump version to 2.1.0 [skip ci]
docs(CONTRIBUTING): Add new sections

Add three new sections: Asking a question, Reporting a bug and Requesting
a feature.
docs(CONTRIBUTING): Update pull request guidelines
fix(tagsInput): Set element's validity when options change

Set element's validity when minTags, maxTags and allowLeftoverText
options change. Other validation options don't need to be monitored
because they are only used upon some user interaction with the directive.

Closes #154
refactor(tagsInput): Add default values to all options

Add default values to all options so some parts of the code become a
bit simpler by not having to check for 'undefined' before using an option.
Introduce a MAX_SAFE_INTEGER constant to be used as an upper bound for
maxTags and maxLength options.
chore(build): Update build files [skip ci]
fix(autocomplete): Fix suggestion selection on touch devices

Perform suggestion selection on mouse click instead of mouse enter so
it works correctly on touch devices.

Close #142
test(tagsInput): Add missing test

Add missing test to ensure the model is correctly initialized.
chore(build): Update build files [skip ci]