v0.5.2

• Added new symbolize_keys helper method for turning the string-key based return hashes into symbol-key based ones
• Added new label_for_measurement helper method to get the correct unit measurement label given a measurement type and the current user's ApiUnitSystem setting
• Added specs
• Added new connected? method on Fitgem::Client that will report whether API calls may be made
• Added InvalidUnitSystem error and InvalidMeasurementType error
• Fixed a small issue where date values were not being formatted correctly in calls to log_body_measurements