ENYO-3129: Display an error message when the values entred into the inputs "Splash screen duration" & "Load URL timeout" are not numbers.

If the error message is displayed the "OK" button on the Pop-up is disable, it will be enabled if the values entred into these inputs are numbers.
ENYO-3129: an error message is displayed under the pickers if the interval the min/max API level isn't correct (min API level value is greater than the max API level value).

notice that if there are two displayed errors on the panel the correction of one of these error will re-enable the 'OK' button of the Pop-up which is an unwanted behaviours.
This issue will be treated in one of the next commits.
ENYO-3129: an error message is displayed under an image path selector (icon & splash screen) if the values of the length and width of the image aren't a numbers
ENYO-3129: Enforce the test on all the Phonegap build UI.

The button Ok will be enabled only if all the value are valides.
ENYO-3129: add a missing semi-column.
ENYO-3129: add a description in the place holder of the inputs "Splash screen duration", "Load url timeout", "length" & "width".
ENYO-3129: change the label "Length" to "Height".
ENYO-3129: disable the inputs of the filechooser widgets in Phonegap build panel.
ENYO-3129: pull request remarks treatment.
ENYO-3129: put the name of the configuration component of the row in camel-case.
ENYO-3129: removed development logs
Merge pull request #597 from enyojs/ENYO-3129

ENYO-3129: Add test on the input value of the Phonegap Build UI.