Merge branch 'master' into develop
Increments gem version to 0.1.5.pre
Adds pack_format to Field::Definition that is derived from the field def's width value
Changes description for ShortRecordError and LongRecordError
Removes dependency on extlib; Adds implementation of blank? from extlib
Increaments gem version to 0.1.5

* Remvoes dependency on ExtLib
* Adds implementation of Blank?
* Changes description for ShortRecordError and LongRecordError
* Adds pack_format to Field::Definition that is derived from the field def's width value
Merge branch 'release/v0.1.5'

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