fix(typeahead): fix loading callback when deleting characters

Closes #1140
fix(tooltip): hide tooltips when content becomes empty

Closes #875
feat(tooltip): add ability to enable / disable tooltip
fix(datapicker): set popup initial position in append-to-body case

Set the initial position offsets of the datepicker popup element in case of appended to 'body'.

Todo: refresh the position on parent elements resize.
feat(dropdownToggle): disable dropdown when it has the disabled class
test(typeahead): corrects typos

Closes #1209
refactor(alert): clean-up unused variables
docs(README): add info about templates customization
docs(README): fix markup
fix(typeahead): prevent accidental form submission on ENTER
fix(datepicker): properly handle showWeeks config option

Closes #1132
docs(modal): fix double "a" typo

Closes #1214
fix(position): correct positioning for SVG elements

Bootstrap tooltips calculate the `width` and `height` of elements
using first getBoundingClientRect and fall back to `offsetWidth` and
`offsetHeight` if it is not available:

https://github.com/twbs/bootstrap/blob/master/js/tooltip.js#L297

This fixes a problem with tooltips/popovers on SVG elements in
Firefox: https://github.com/twbs/bootstrap/issues/5956

This change mimics that behavior.

Closes #1225
fix(typeahead): evaluate matches source against a correct scope

Closes #1238
fix(collapse): remove element height watching

For unclear reasons the directive was watching DOM element's height
which incurs performance penalty. Normally this watching shouldn't be
necessery as collapsible elements should get height: auto;

Closes #1222
fix(collapse): add the "in" class for expanded panels

Closes #1192
chore(readme): add a note in readme about custom build
docs(README): info on building a subset of modules
refactor(modal): remove unused templates
style(all): rename test files to keep extensions consistent