Update requirements, handle more lemur_acme exceptions, and remove take a tour button

lemur/plugins/lemur_acme/plugin.py

@@ -304,7 +304,7 @@ class ACMEIssuerPlugin(IssuerPlugin):
                     "cert": cert,
                     "pending_cert": entry["pending_cert"],
                 })
-            except (PollError, AcmeError):
+            except (PollError, AcmeError, Exception):
                 current_app.logger.error("Unable to resolve pending cert: {}".format(pending_cert), exc_info=True)
                 certs.append({
                     "cert": False,

lemur/static/app/angular/welcome/welcome.html

@@ -1,5 +1,4 @@
 <div class="jumbotron">
-  <span class="pull-right"><button class="btn btn-sm btn-primary">First Time? Take the Tour!</button></span>
   <h1>Hey there!</h1>
   <p>Welcome to Lemur! A central portal for all (most) of your TLS certificate needs. With Lemur you are able to create, deploy and track the TLS certificates in your environment. Lets get started!</p>
 </div>