Corrected transaction modes.
Corrected transaction modes.

If the user specifies a valid string or numeric value, the mode passes
through transparently, otherwise read_write mode is applied. 

Note: It is best to use browser constants for modes as they are
supported by earlier versions also. 
axemclion/jquery-indexeddb,axemclion/jquery-indexeddb,axemclion/jquery-indexeddb