OutOfMemory error when exporting/importing large Bamboo instances

The Bamboo export/import process is highly inefficient

The import process reads all XML files to memory and the SAX parser tries to parse the files off memory. For a (uncompressed) xml file size 1mb - Bamboo uses up about 7 mb of memory - this causes issues such as https://support.atlassian.com/browse/BSP-285. Where the customers exported zip file is ~50mb, this translates into about 350-400mb of uncompressed XML files being parsed by Bamboo, which requires upwards of ~3gb of heap space to be parsed successfully.

As Bamboo instances grow with time, we can expect the Bamboo-Home exports to be massive and this issue must be addressed A.S.A.P.