Fix bug in ConcatColumn#reindex.
A bug that was seen once but I cannot reproduce.
Merge pull request #47 from pellucidanalytics/fix/concatcolumn-reindex

Fix bug in ConcatColumn#reindex.
Merge pull request #48 from pellucidanalytics/fix/rowview-ioobe

A bug that was seen once but I cannot reproduce.
Bump version to 0.2.4.