Raven_Client::send_http() call to undefined method

Raven_Client::send_http_asynchronous_exec() method does not exist, replace with send_http_asynchronous_curl_exec.
Merge pull request #163 from yanickj/master

Raven_Client::send_http() call to undefined method
Added PHP 5.6, 5.5 and HHVM to travis.yml
Merge pull request #164 from Nyholm/patch-1

Added PHP 5.6, 5.5 and HHVM to travis.yml
Fix level detection in Raven_Client::captureException()
Tabs to whitespaces
Fix custom json function

Use correct cycle to check if array is numerical or map
Add tests to CompatTest
Merge pull request #165 from jkrcma/exceptions-level

Fix level detection in Raven_Client::captureException()
Merge pull request #166 from allevo/fix/custom-json-function

Fix custom json function