Netpyne-ui

**New Features**
- New AppBar component with a different interaction for the user for the instantiation and simulation processes.
- Export/Import to/from a python file.
- Export/Import to/from a json file.
- New Tabbed Drawer component introduced for the JS and Python console.
- CellParams hierarchy improved to help the users during the navigation.
- Added RxD plot.
- New Logo and colors.
- Netpyne-UI migrated to the latest jupyter notebook library.
- Geppetto jupyter extension and synch component between JS frontend and python backend refactoring for code wise and performance improvements.
- Name validation feature, now checking for valid chars in the string and as well for collision with a name already present.
- Casper tests coverage extended.

**Fixes**
- Fixed the format type validation for data inserted by the user.
- Fixed conds in the netParams.stimTargetParams that should be empty and before was populated with an empty Population.
- Fixed the default value in connectivity rules that should be empty by default.
- Fixed sections displayed per CellRule whereby before all the sections were displayed.
- Fixed rename for netpyne stimulation source.
- Fixed an issue where if the name of an element of the UI (e.g. Population) was renamed with an empty string therefore the element was inaccessible in a second moment.
- Fixed an issue whereby if the same name was used for the same component type (e.g. cellRule), the 2 components were colliding into a single one on the frontend side but not on the backed.
- Fixed the coordinateRange component synchronization between frontend and backend when a component using this component was renamed.

**New Features**
- Automation testing implemented with CasperJS.
- Added configurable plots for simulation.
- Added stimulation sources, stimulation targets and synapse mechanisms.
- Cell template can now be imported into CellRules.
- Added density mechanism.
- Added network attributes.
- Improved the import for model and cells with the implementation of a file browser.
- Delete buttons on hover implemented to delete a components (e.g. Population, CellRule, etc.) and not the entire model.
- Added the timeRange component to handle beginning and end time frames.
- Implemented an error handler.
- The GUI now supports pypi installation, docker file and virtualbox image.


**Fixes**
- some tabs some(e.g. synMechParams) were not displaying the data after coming back from the instantiation window.
- Fixed an issue in the Population's spatial distribution configuration with min and max axis that were not handling correctly decimal values and special characters.
- Fixed with the rename of the stimuatlion sources and stimulation targets.
- Fixed the synchParams not appearing in the synMechs.
- Fixed the LFP plot now showing properly.
- Fixed the dialog transition for import cell template and import model due to the spinner that was overlapping with the dialog.

- 🎉 first release!