Doc string updates, error changes, and travis fixes

Author: Aodhan Sweeney

examples/HurricaneTracker.py

@@ -5,8 +5,8 @@
 
 This GUI takes data pulled from the National
 Hurricane Center and plots specific storms and
-their tracks. The GUI runs using ipwidgets, and
-is intended to be used as an ipython notebook.
+their tracks. The GUI runs using ipywidgets, and
+is intended to be used as an Jupyter notebook.
 """
 
 import cartopy.crs as ccrs
@@ -77,7 +77,7 @@ def get_name_dropdown(self, storm_names):
         if self.filename.empty is False:
             self.filename = file_name[0]
         elif self.filename.empty is True:
-            raise Exception('ValueError: No file name data for this year.')
+            raise ValueError('No data for specific file name of the chosen.')
 
     def get_track(self, track_button):
         """

examples/SPCTracker.py

@@ -24,8 +24,8 @@ class SPC_GUI:
     """
     Graphic User Interface designed to allow users to access Storm Prediction Center data.
 
-    This class uses ipython widgets. NOTE: storm chosen must be after 2011 because methods
-    of data parsing are different and will not work for dates earlier.
+    This class uses ipython widgets. NOTE: date chosen must be from 2011 to present because
+    methods of data parsing are different and will not work for dates earlier.
     """
     def __init__(self):
         """
@@ -71,7 +71,7 @@ def fetch_spc(self, stormpicker):
             one_storm_type = spc.SPCD(storm_type, self.date_string)
             # Storm must be after year 2011
             if int(self.date_string[:4]) < 2011:
-                one_storm_type = one_storm_type.day_table[['Time', 'Start Lat', 'Start Lon']]
+                raise ValueError('SPC GUI does not support events before 2012.')
             self.spc_data_table.append(one_storm_type.day_table)
 
         if self.spc_data_table != []:
@@ -83,7 +83,7 @@ def fetch_spc(self, stormpicker):
             self.all_events = self.all_events.sort_index()
 
             if self.all_events.empty:
-                raise Exception("Value Error: Can\'t plot a storm event that doesn\'t exist.")
+                raise ValueError('No storm reports of any type for this date.')
 
             self.plot_slider = widgets.IntSlider(min=0, max=(len(self.all_events)-1),
                                                  value=0, description='Event #',