Add React component for country creation

[php-coder]

We need to port existing form for country creation to React. Here is the current code:

mystamps/src/main/webapp/WEB-INF/views/country/add.html

Lines 76 to 112 in 366f099

	<form id="add-country-form" method="post" class="form-horizontal" action="info.html"
	th:action="@{${ADD_COUNTRY_PAGE}}" th:object="${addCountryForm}">
	<div class="form-group" th:classappend="${#fields.hasErrors('name') ? 'has-error' : ''}">
	<label for="name" class="control-label col-sm-4">
	<span th:remove="tag" th:text="#{t_name_in_english}">
	Name (in English)
	</span>
	<span class="required_field">*</span>
	</label>
	<div class="col-sm-5">
	<input id="name" type="text" class="form-control" required="required" th:field="*{name}" />
	<!--/*/
	<span id="name.errors" class="help-block" th:if="${#fields.hasErrors('name')}" th:each="error : ${#fields.errors('name')}" th:text="${error}"></span>
	/*/-->
	</div>
	</div>
	<div class="form-group" th:classappend="${#fields.hasErrors('nameRu') ? 'has-error' : ''}">
	<label for="nameRu" class="control-label col-sm-4" th:text="#{t_name_in_russian}">
	Name (in Russian)
	</label>
	<div class="col-sm-5">
	<input id="nameRu" type="text" class="form-control" th:field="*{nameRu}" />
	<!--/*/
	<span id="nameRu.errors" class="help-block" th:if="${#fields.hasErrors('nameRu')}" th:each="error : ${#fields.errors('nameRu')}" th:text="${error}"></span>
	/*/-->
	</div>
	</div>
	<div class="form-group">
	<div class="col-sm-offset-4 col-sm-5">
	<input type="submit" class="btn btn-primary" value="Add" th:value="#{t_add}" />
	</div>
	</div>
	</form>

When a user submits data, we should POST it to /categories Also, we should handle&show related errors from a server.

As part of this task we should only create a React component. API call will be implemented in #1347 Unit and integration tests, will be added later.

Part of #1328