Merge pull request #170 from just-boris/master

handle small values in statistics
added clear storage events : for steps and tests
added test for clearing events
events now added through xsd
Merge pull request #172 from sidelikovmike/master

Adding clear storage events
Update allure.events.xsd
add test to bug #173
fixes #173
fixes #158
invalid xml characters test
Merge pull request #174 from baev/model-refactoring

some bug fixes
[maven-release-plugin] prepare release allure-core-1.3.4
[maven-release-plugin] prepare for next development iteration
show stacktrace beside the step
closes #175