add validator checkbox_group, plus utility for numeric range

checkbox_group
added validator to check a group of checkboxes, to ensure required number of checkboxes were checked, using range (1-2), min1, or max2, etc.

lang
added prefix & suffixes for checkbox_group
renamed prefixes & suffixes used for length validation

numericRangeCheck 
added utility function to evaluate value against allowed parameter. abstracted internal check in validate_length to use this util function instead of repeating functionality

vaildate_length
edited function to use new utility function numericRangeCheck
add new code descriptions

for validator checkbox groups
and variable name changes
input field selector onblur, name changes

jQ selector of form inputs for onBlur, only select input that have attribute "data-validation", this skips form elements with no validation, including submits, buttons, and reset

i was going crazy debugging this when every function was named validate, dovalidate, validateInput, etc. 
so i renamed them based on what they did.
thanks
bug fix numericRangeCheck, bug fix checkbox_group

numericRangeCheck had bug in conditional structure; fixed.

checkbox_group had bug when checking checkboxes in same group.
added special test in validateInput() function, to force element to be first input element in group, so error msg only output once. also changed .append back to .text to support this case.
Merge pull request #42 from stevewasiura/patch-10

add validator checkbox_group, plus utility for numeric range