Github Connector now takes the fact that a request might fail into account.
Minor refactoring and fixes to comments.

 - Makes the comment above the Core/Context class an actual docblock.
 - Adds missing opening slash to namespace in a dockblock for Core/LogEntry::getTime()
 - Improves various dockBlocks and IDE comments in Core/TimeLog and refactors TimeLog::outputTaskTotalTime()
 - Improves various dockBlocks and IDE comments in Connectors/Local/LocalConnector and refactors LocalConnector::provideHistory()