Fix get-profile and get-all-sensors when missing link

[BenMatase]

For instance, when there is a missing device or a project, the entire endpoint crashes because it tries to make a DB call that looks like

2018-04-17 20:12:36,381 - api - ERROR - Couldn't execute query - b'SELECT * FROM project WHERE projectId IN ()'
Traceback (most recent call last):
  File "/nfs/unixspace/linux/accounts/courtesy/e/energyhill/public_html/Flower/backend/db.py", line 61, in exec_query
    cursor.execute(formatted_sql_string, param_tuple)
  File "/usr/remote/anaconda-3.6/lib/python3.6/site-packages/MySQLdb/cursors.py", line 250, in execute
    self.errorhandler(self, exc, value)
  File "/usr/remote/anaconda-3.6/lib/python3.6/site-packages/MySQLdb/connections.py", line 50, in defaulterrorhandler
    raise errorvalue
  File "/usr/remote/anaconda-3.6/lib/python3.6/site-packages/MySQLdb/cursors.py", line 247, in execute
    res = self._query(query)
  File "/usr/remote/anaconda-3.6/lib/python3.6/site-packages/MySQLdb/cursors.py", line 411, in _query
    rowcount = self._do_query(q)
  File "/usr/remote/anaconda-3.6/lib/python3.6/site-packages/MySQLdb/cursors.py", line 374, in _do_query
    db.query(q)
  File "/usr/remote/anaconda-3.6/lib/python3.6/site-packages/MySQLdb/connections.py", line 292, in query
    _mysql.connection.query(self, query)
_mysql_exceptions.ProgrammingError: (1064, "You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ')' at line 1")