In HDF5 constructors, change the mode from 'w'rite to 'a'ppend.
In HDF5 constructors, change the mode from 'w'rite to 'a'ppend.

This is in order to not re-write the underlying file.  This
change from 'w'rite mode into 'a'ppend might be a bit misleading
and should be revisited in the future, but for now will do.

ChinaQuants/blaze,jcrist/blaze,xlhtc007/blaze,cpcloud/blaze,mrocklin/blaze,aterrel/blaze,jdmcbr/blaze,maxalbert/blaze,LiaoPan/blaze,maxalbert/blaze,cpcloud/blaze,alexmojaki/blaze,LiaoPan/blaze,ContinuumIO/blaze,FrancescAlted/blaze,aterrel/blaze,dwillmer/blaze,caseyclements/blaze,aterrel/blaze,FrancescAlted/blaze,cowlicks/blaze,FrancescAlted/blaze,scls19fr/blaze,jcrist/blaze,scls19fr/blaze,FrancescAlted/blaze,xlhtc007/blaze,cowlicks/blaze,dwillmer/blaze,caseyclements/blaze,nkhuyu/blaze,alexmojaki/blaze,jdmcbr/blaze,mrocklin/blaze,ChinaQuants/blaze,nkhuyu/blaze,ContinuumIO/blaze