Fix DataTables rendering with bootstrap 4

cellspacing="0" : to avoid double lines in the header
width="100%" : to have extra fields (search, paging...) aligned properly with
the table

app/templates/inventory/attributes.html

@@ -26,7 +26,7 @@
 
   <hr class="separator">
 
-  <table id="attributes_table" class="table table-bordered table-hover table-sm">
+  <table id="attributes_table" class="table table-bordered table-hover table-sm" cellspacing="0" width="100%">
     <thead>
       <tr>
         <th>Name</th>

app/templates/inventory/items.html

@@ -14,7 +14,7 @@
 
   <br>
 
-  <table id="items_table" class="table table-bordered table-hover table-sm">
+  <table id="items_table" class="table table-bordered table-hover table-sm" cellspacing="0" width="100%">
     <thead>
       <tr>
         <th>Id</th>

app/templates/network/hosts.html

@@ -14,7 +14,7 @@
 
   <br>
 
-  <table id="hosts_table" class="table table-bordered table-hover table-sm">
+  <table id="hosts_table" class="table table-bordered table-hover table-sm" cellspacing="0" width="100%">
     <thead>
       <tr>
         <th>Hostname</th>

app/templates/network/networks.html

@@ -14,7 +14,7 @@
 
   <br>
 
-  <table id="networks_table" class="table table-bordered table-hover table-sm">
+  <table id="networks_table" class="table table-bordered table-hover table-sm" cellspacing="0" width="100%">
     <thead>
       <tr>
         <th>Network scope</th>