Proxy support (#44)

* add proxy support

* return as data frame

src/jobspy/scrapers/exceptions.py

@@ -0,0 +1,18 @@
+"""
+jobspy.scrapers.exceptions
+~~~~~~~~~~~~~~~~~~~
+
+This module contains the set of Scrapers' exceptions.
+"""
+
+
+class LinkedInException(Exception):
+    """Failed to scrape LinkedIn"""
+
+
+class IndeedException(Exception):
+    """Failed to scrape Indeed"""
+
+
+class ZipRecruiterException(Exception):
+    """Failed to scrape ZipRecruiter"""