Fix for ContainerAsyncRequest.getCompilerErrors behaviour change in Summer 14 Orgs

in Summer'14 SFDC broke ContainerAsyncRequest.getCompilerErrors
for every field in getCompilerErrors() JSON - SFDC Orgs starting Summer'14 return JSON arrays instead of normal
values, even though we are calling SFDC with API v29.0, so have to check value type (Any or JSONArray) first