fix(button): improve outline button appearance

fix(button): improve outline button appearance

docs(vue): Add Theme preview app

fix(buttonGroup): fix no applying focus state to disabled button in b…

…utton group telerik/kendo#7846

chore(travis): workaround travis failures

fix(multiselect): improve height of token with empty string telerik/k…

…endo-ui-core#372

fix(spreadsheet): improve spreadsheet active cell border by frozen ce…

…lls telerik/kendo-ui-core#3254

fix(spreadsheet): improve spreadsheet active cell border by frozen ce…

…lls telerik/kendo-ui-core#3254

docs(preview): add support for react theme-preview example (#355)

* docs(preview): add support for react theme-preview example

* docs(preview): add react example height

* docs: add a minor fix

fix(dateinputs): apply consistent header styles

see telerik/kendo-theme-bootstrap/#350