Add support for BooleanField to field templatetag and *field.html templates

Since checkboxes are not normally serialized when they are not checked,
inlineEditForm.js and fieldHelpers.js are handling checkboxes separately
from text inputs and selects, and always send true/false when serializing
Add read-only field to plot detail
Merge pull request #275 from maurizi/topic/booleanFields

Topic/boolean fields
Merge branch 'master' of github.com:azavea/OTM2